diff --git a/src/System.CommandLine.ApiCompatibility.Tests/ApiCompatibilityApprovalTests.System_CommandLine_api_is_not_changed.approved.txt b/src/System.CommandLine.ApiCompatibility.Tests/ApiCompatibilityApprovalTests.System_CommandLine_api_is_not_changed.approved.txt
index dafb0cfd4c..b4f8bea74f 100644
--- a/src/System.CommandLine.ApiCompatibility.Tests/ApiCompatibilityApprovalTests.System_CommandLine_api_is_not_changed.approved.txt
+++ b/src/System.CommandLine.ApiCompatibility.Tests/ApiCompatibilityApprovalTests.System_CommandLine_api_is_not_changed.approved.txt
@@ -5,9 +5,17 @@ System.CommandLine
     public System.Boolean HasDefaultValue { get; }
     public System.String HelpName { get; set; }
     public System.Type ValueType { get; }
+    public Argument AcceptLegalFileNamesOnly()
+    public Argument AcceptLegalFilePathsOnly()
+    public Argument AcceptOnlyFromAmong(System.String[] values)
+    public Argument AddCompletions(System.String[] completions)
+    public Argument AddCompletions(System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.String>> completionsDelegate)
+    public Argument AddCompletions(System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.CommandLine.Completions.CompletionItem>> completionsDelegate)
     public System.Void AddValidator(System.Action<System.CommandLine.Parsing.ArgumentResult> validate)
     public System.Collections.Generic.IEnumerable<System.CommandLine.Completions.CompletionItem> GetCompletions(System.CommandLine.Completions.CompletionContext context)
     public System.Object GetDefaultValue()
+    public ParseResult Parse(System.String commandLine)
+    public ParseResult Parse(System.String[] args)
     public System.Void SetDefaultValue(System.Object value)
     public System.Void SetDefaultValueFactory(System.Func<System.Object> defaultValueFactory)
     public System.Void SetDefaultValueFactory(System.Func<System.CommandLine.Parsing.ArgumentResult,System.Object> defaultValueFactory)
@@ -32,19 +40,11 @@ System.CommandLine
     public System.Boolean Equals(ArgumentArity other)
     public System.Boolean Equals(System.Object obj)
     public System.Int32 GetHashCode()
-  public static class ArgumentExtensions
-    public static TArgument AddCompletions<TArgument>(this TArgument argument, System.String[] values)
-    public static TArgument AddCompletions<TArgument>(this TArgument argument, System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.String>> complete)
-    public static TArgument AddCompletions<TArgument>(this TArgument argument, System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.CommandLine.Completions.CompletionItem>> complete)
-    public static Argument<System.IO.FileInfo> ExistingOnly(this Argument<System.IO.FileInfo> argument)
-    public static Argument<System.IO.DirectoryInfo> ExistingOnly(this Argument<System.IO.DirectoryInfo> argument)
-    public static Argument<System.IO.FileSystemInfo> ExistingOnly(this Argument<System.IO.FileSystemInfo> argument)
-    public static Argument<T> ExistingOnly<T>(this Argument<T> argument)
-    public static TArgument FromAmong<TArgument>(this TArgument argument, System.String[] values)
-    public static TArgument LegalFileNamesOnly<TArgument>(this TArgument argument)
-    public static TArgument LegalFilePathsOnly<TArgument>(this TArgument argument)
-    public static ParseResult Parse(this Argument argument, System.String commandLine)
-    public static ParseResult Parse(this Argument argument, System.String[] args)
+  public static class ArgumentValidation
+    public static Argument<System.IO.FileInfo> AcceptExistingOnly(this Argument<System.IO.FileInfo> argument)
+    public static Argument<System.IO.DirectoryInfo> AcceptExistingOnly(this Argument<System.IO.DirectoryInfo> argument)
+    public static Argument<System.IO.FileSystemInfo> AcceptExistingOnly(this Argument<System.IO.FileSystemInfo> argument)
+    public static Argument<T> AcceptExistingOnly<T>(this Argument<T> argument)
   public class Command : IdentifierSymbol, System.Collections.Generic.IEnumerable<Symbol>, System.Collections.IEnumerable
     .ctor(System.String name, System.String description = null)
     public System.Collections.Generic.IReadOnlyList<Argument> Arguments { get; }
@@ -109,7 +109,7 @@ System.CommandLine
     .ctor()
     .ctor(System.String message, System.Exception innerException)
   public static class CompletionSourceExtensions
-    public static System.Void Add(this System.Collections.Generic.ICollection<System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.CommandLine.Completions.CompletionItem>>> completionSources, System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.String>> complete)
+    public static System.Void Add(this System.Collections.Generic.ICollection<System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.CommandLine.Completions.CompletionItem>>> completionSources, System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.String>> completionsDelegate)
     public static System.Void Add(this System.Collections.Generic.ICollection<System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.CommandLine.Completions.CompletionItem>>> completionSources, System.String[] completions)
   public static class ConsoleExtensions
     public static System.Void Write(this IConsole console, System.String value)
@@ -193,9 +193,17 @@ System.CommandLine
     public ArgumentArity Arity { get; set; }
     public System.Boolean IsRequired { get; set; }
     public System.Type ValueType { get; }
+    public Option AcceptLegalFileNamesOnly()
+    public Option AcceptLegalFilePathsOnly()
+    public Option AcceptOnlyFromAmong(System.String[] values)
+    public Option AddCompletions(System.String[] completions)
+    public Option AddCompletions(System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.String>> completionsDelegate)
+    public Option AddCompletions(System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.CommandLine.Completions.CompletionItem>> completionsDelegate)
     public System.Void AddValidator(System.Action<System.CommandLine.Parsing.OptionResult> validate)
     public System.Collections.Generic.IEnumerable<System.CommandLine.Completions.CompletionItem> GetCompletions(System.CommandLine.Completions.CompletionContext context)
     public System.Boolean HasAliasIgnoringPrefix(System.String alias)
+    public ParseResult Parse(System.String commandLine)
+    public ParseResult Parse(System.String[] args)
     public System.Void SetDefaultValue(System.Object value)
     public System.Void SetDefaultValueFactory(System.Func<System.Object> defaultValueFactory)
   public class Option<T> : Option, IValueDescriptor<T>, System.CommandLine.Binding.IValueDescriptor
@@ -205,19 +213,11 @@ System.CommandLine
     .ctor(System.String[] aliases, Func<System.CommandLine.Parsing.ArgumentResult,T> parseArgument, System.Boolean isDefault = False, System.String description = null)
     .ctor(System.String name, Func<T> defaultValueFactory, System.String description = null)
     .ctor(System.String[] aliases, Func<T> defaultValueFactory, System.String description = null)
-  public static class OptionExtensions
-    public static TOption AddCompletions<TOption>(this TOption option, System.String[] values)
-    public static TOption AddCompletions<TOption>(this TOption option, System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.String>> complete)
-    public static TOption AddCompletions<TOption>(this TOption option, System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.CommandLine.Completions.CompletionItem>> complete)
-    public static Option<System.IO.FileInfo> ExistingOnly(this Option<System.IO.FileInfo> option)
-    public static Option<System.IO.DirectoryInfo> ExistingOnly(this Option<System.IO.DirectoryInfo> option)
-    public static Option<System.IO.FileSystemInfo> ExistingOnly(this Option<System.IO.FileSystemInfo> option)
-    public static Option<T> ExistingOnly<T>(this Option<T> option)
-    public static TOption FromAmong<TOption>(this TOption option, System.String[] values)
-    public static TOption LegalFileNamesOnly<TOption>(this TOption option)
-    public static TOption LegalFilePathsOnly<TOption>(this TOption option)
-    public static ParseResult Parse(this Option option, System.String commandLine)
-    public static ParseResult Parse(this Option option, System.String[] args)
+  public static class OptionValidation
+    public static Option<System.IO.FileInfo> AcceptExistingOnly(this Option<System.IO.FileInfo> option)
+    public static Option<System.IO.DirectoryInfo> AcceptExistingOnly(this Option<System.IO.DirectoryInfo> option)
+    public static Option<System.IO.FileSystemInfo> AcceptExistingOnly(this Option<System.IO.FileSystemInfo> option)
+    public static Option<T> AcceptExistingOnly<T>(this Option<T> option)
   public class ParseResult
     public System.CommandLine.Parsing.CommandResult CommandResult { get; }
     public System.Collections.Generic.IReadOnlyDictionary<System.String,System.Collections.Generic.IReadOnlyList<System.String>> Directives { get; }
diff --git a/src/System.CommandLine.Suggest/SuggestionDispatcher.cs b/src/System.CommandLine.Suggest/SuggestionDispatcher.cs
index 0a350926d3..6c36afb9e8 100644
--- a/src/System.CommandLine.Suggest/SuggestionDispatcher.cs
+++ b/src/System.CommandLine.Suggest/SuggestionDispatcher.cs
@@ -89,9 +89,15 @@ public SuggestionDispatcher(ISuggestionRegistration suggestionRegistration, ISug
 
         private Command GetCommand { get; }
 
-        private Option<FileInfo> ExecutableOption { get; } =
-            new Option<FileInfo>(new[] { "-e", "--executable" }, "The executable to call for suggestions")
-                .LegalFilePathsOnly();
+        private Option<FileInfo> ExecutableOption { get; } = GetExecutableOption();
+
+        private static Option<FileInfo> GetExecutableOption()
+        {
+            var option = new Option<FileInfo>(new[] { "-e", "--executable" }, "The executable to call for suggestions");
+            option.AcceptLegalFilePathsOnly();
+
+            return option;
+        }
 
         private Command ListCommand { get; }
 
diff --git a/src/System.CommandLine.Tests/ArgumentTests.cs b/src/System.CommandLine.Tests/ArgumentTests.cs
index 84abe6f2cd..18006d1e3b 100644
--- a/src/System.CommandLine.Tests/ArgumentTests.cs
+++ b/src/System.CommandLine.Tests/ArgumentTests.cs
@@ -769,7 +769,7 @@ public void OnlyTake_can_pass_on_all_tokens_from_a_single_arity_argument_to_anot
         public void Argument_of_enum_can_limit_enum_members_as_valid_values()
         {
             var argument = new Argument<ConsoleColor>()
-                .FromAmong(ConsoleColor.Red.ToString(), ConsoleColor.Green.ToString());
+                .AcceptOnlyFromAmong(ConsoleColor.Red.ToString(), ConsoleColor.Green.ToString());
             Command command = new("set-color")
             {
                 argument
diff --git a/src/System.CommandLine.Tests/CompletionContextTests.cs b/src/System.CommandLine.Tests/CompletionContextTests.cs
index 83dfa3ec35..4090dfd430 100644
--- a/src/System.CommandLine.Tests/CompletionContextTests.cs
+++ b/src/System.CommandLine.Tests/CompletionContextTests.cs
@@ -112,7 +112,7 @@ public void When_position_is_greater_than_input_length_in_a_string_command_line_
             var command = new Command("the-command")
             {
                 new Argument<string>(),
-                new Option<string>("--option1").FromAmong("apple", "banana", "cherry", "durian"),
+                new Option<string>("--option1").AcceptOnlyFromAmong("apple", "banana", "cherry", "durian"),
                 new Option<string>("--option2")
             };
 
@@ -178,7 +178,7 @@ public void When_position_is_unspecified_in_array_command_line_and_final_token_m
         {
             var command = new Command("the-command")
             {
-                new Option<string>("--option1").FromAmong("apple", "banana", "cherry", "durian"),
+                new Option<string>("--option1").AcceptOnlyFromAmong("apple", "banana", "cherry", "durian"),
                 new Option<string>("--option2"),
                 new Argument<string>()
             };
diff --git a/src/System.CommandLine.Tests/CompletionTests.cs b/src/System.CommandLine.Tests/CompletionTests.cs
index 67e59ea177..0597bb6d94 100644
--- a/src/System.CommandLine.Tests/CompletionTests.cs
+++ b/src/System.CommandLine.Tests/CompletionTests.cs
@@ -438,8 +438,8 @@ public void Parser_options_can_supply_context_sensitive_matches()
         {
             var parser = new RootCommand
             {
-                new Option<string>("--bread").FromAmong("wheat", "sourdough", "rye"),
-                new Option<string>("--cheese").FromAmong("provolone", "cheddar", "cream cheese")
+                new Option<string>("--bread").AcceptOnlyFromAmong("wheat", "sourdough", "rye"),
+                new Option<string>("--cheese").AcceptOnlyFromAmong("provolone", "cheddar", "cream cheese")
             };
 
             var commandLine = "--bread";
@@ -543,8 +543,8 @@ public void Argument_completions_can_be_based_on_the_proximate_option()
             var parser = new Parser(
                 new Command("outer")
                 {
-                    new Option<string>("--one").FromAmong("one-a", "one-b"),
-                    new Option<string>("--two").FromAmong("two-a", "two-b")
+                    new Option<string>("--one").AcceptOnlyFromAmong("one-a", "one-b"),
+                    new Option<string>("--two").AcceptOnlyFromAmong("two-a", "two-b")
                 });
 
             var commandLine = "outer --two";
@@ -642,11 +642,11 @@ public void When_caller_does_the_tokenizing_then_argument_completions_are_based_
             var command = new Command("outer")
             {
                 new Option<string>("one")
-                    .FromAmong("one-a", "one-b", "one-c"),
+                    .AcceptOnlyFromAmong("one-a", "one-b", "one-c"),
                 new Option<string>("two")
-                    .FromAmong("two-a", "two-b", "two-c"),
+                    .AcceptOnlyFromAmong("two-a", "two-b", "two-c"),
                 new Option<string>("three")
-                    .FromAmong("three-a", "three-b", "three-c")
+                    .AcceptOnlyFromAmong("three-a", "three-b", "three-c")
             };
 
             var parser = new CommandLineBuilder(new RootCommand
@@ -669,11 +669,11 @@ public void When_parsing_from_array_then_argument_completions_are_based_on_the_p
             var command = new Command("outer")
             {
                 new Option<string>("one")
-                    .FromAmong("one-a", "one-b", "one-c"),
+                    .AcceptOnlyFromAmong("one-a", "one-b", "one-c"),
                 new Option<string>("two")
-                    .FromAmong("two-a", "two-b", "two-c"),
+                    .AcceptOnlyFromAmong("two-a", "two-b", "two-c"),
                 new Option<string>("three")
-                    .FromAmong("three-a", "three-b", "three-c")
+                    .AcceptOnlyFromAmong("three-a", "three-b", "three-c")
             };
 
             var result = command.Parse("outer two b");
@@ -691,15 +691,15 @@ public void When_parsing_from_text_then_argument_completions_are_based_on_the_pr
             {
                 new Command("one")
                 {
-                    new Argument<string>().FromAmong("one-a", "one-b", "one-c")
+                    new Argument<string>().AcceptOnlyFromAmong("one-a", "one-b", "one-c")
                 },
                 new Command("two")
                 {
-                    new Argument<string>().FromAmong("two-a", "two-b", "two-c")
+                    new Argument<string>().AcceptOnlyFromAmong("two-a", "two-b", "two-c")
                 },
                 new Command("three")
                 {
-                    new Argument<string>().FromAmong("three-a", "three-b", "three-c")
+                    new Argument<string>().AcceptOnlyFromAmong("three-a", "three-b", "three-c")
                 }
             };
 
@@ -718,15 +718,15 @@ public void When_parsing_from_array_then_argument_completions_are_based_on_the_p
             {
                 new Command("one")
                 {
-                    new Argument<string>().FromAmong("one-a", "one-b", "one-c")
+                    new Argument<string>().AcceptOnlyFromAmong("one-a", "one-b", "one-c")
                 },
                 new Command("two")
                 {
-                    new Argument<string>().FromAmong("two-a", "two-b", "two-c")
+                    new Argument<string>().AcceptOnlyFromAmong("two-a", "two-b", "two-c")
                 },
                 new Command("three")
                 {
-                    new Argument<string>().FromAmong("three-a", "three-b", "three-c")
+                    new Argument<string>().AcceptOnlyFromAmong("three-a", "three-b", "three-c")
                 }
             };
 
@@ -743,8 +743,8 @@ public void When_parsing_from_text_if_the_proximate_option_is_completed_then_com
         {
             var command = new RootCommand
             {
-                new Option<string>("--framework").FromAmong("net7.0"),
-                new Option<string>("--language").FromAmong("C#"),
+                new Option<string>("--framework").AcceptOnlyFromAmong("net7.0"),
+                new Option<string>("--language").AcceptOnlyFromAmong("C#"),
                 new Option<string>("--langVersion")
             };
             var parser = new CommandLineBuilder(command).Build();
@@ -760,8 +760,8 @@ public void When_parsing_from_array_if_the_proximate_option_is_completed_then_co
         {
             var command = new RootCommand
             {
-                new Option<string>("--framework").FromAmong("net7.0"),
-                new Option<string>("--language").FromAmong("C#"),
+                new Option<string>("--framework").AcceptOnlyFromAmong("net7.0"),
+                new Option<string>("--language").AcceptOnlyFromAmong("C#"),
                 new Option<string>("--langVersion")
             };
             var parser = new CommandLineBuilder(command).Build();
diff --git a/src/System.CommandLine.Tests/OptionTests.cs b/src/System.CommandLine.Tests/OptionTests.cs
index 1812bffe71..a4d4fd37f9 100644
--- a/src/System.CommandLine.Tests/OptionTests.cs
+++ b/src/System.CommandLine.Tests/OptionTests.cs
@@ -375,7 +375,7 @@ public void Option_of_boolean_defaults_to_false_when_not_specified()
         public void Option_of_enum_can_limit_enum_members_as_valid_values()
         {
             var option = new Option<ConsoleColor>("--color")
-                .FromAmong(ConsoleColor.Red.ToString(), ConsoleColor.Green.ToString());
+                .AcceptOnlyFromAmong(ConsoleColor.Red.ToString(), ConsoleColor.Green.ToString());
 
             var result = option.Parse("--color Fuschia");
 
diff --git a/src/System.CommandLine.Tests/ParseDiagramTests.cs b/src/System.CommandLine.Tests/ParseDiagramTests.cs
index e1cfd8bf45..c5812b27b0 100644
--- a/src/System.CommandLine.Tests/ParseDiagramTests.cs
+++ b/src/System.CommandLine.Tests/ParseDiagramTests.cs
@@ -34,7 +34,7 @@ public void Parse_result_diagram_displays_unmatched_tokens()
         {
             var command = new Command("command")
             {
-                new Option<string>("-x").FromAmong("arg1", "arg2", "arg3")
+                new Option<string>("-x").AcceptOnlyFromAmong("arg1", "arg2", "arg3")
             };
 
             var result = command.Parse("command -x ar");
diff --git a/src/System.CommandLine.Tests/ParserTests.cs b/src/System.CommandLine.Tests/ParserTests.cs
index 6878f12328..103a10f646 100644
--- a/src/System.CommandLine.Tests/ParserTests.cs
+++ b/src/System.CommandLine.Tests/ParserTests.cs
@@ -351,7 +351,7 @@ public void Parser_root_Options_can_be_specified_multiple_times_and_their_argume
         public void Options_can_be_specified_multiple_times_and_their_arguments_are_collated()
         {
             var animalsOption = new Option<string[]>(new[] { "-a", "--animals" })
-                .FromAmong("dog", "cat", "sheep");
+                .AcceptOnlyFromAmong("dog", "cat", "sheep");
             var vegetablesOption = new Option<string[]>(new[] { "-v", "--vegetables" });
             var parser = new Parser(
                 new Command("the-command") {
diff --git a/src/System.CommandLine.Tests/ParsingValidationTests.cs b/src/System.CommandLine.Tests/ParsingValidationTests.cs
index 1416cb282e..2d66518ac3 100644
--- a/src/System.CommandLine.Tests/ParsingValidationTests.cs
+++ b/src/System.CommandLine.Tests/ParsingValidationTests.cs
@@ -25,7 +25,7 @@ public ParsingValidationTests(ITestOutputHelper output)
         public void When_an_option_accepts_only_specific_arguments_but_a_wrong_one_is_supplied_then_an_informative_error_is_returned()
         {
             var option = new Option<string>("-x")
-                .FromAmong("this", "that", "the-other-thing");
+                .AcceptOnlyFromAmong("this", "that", "the-other-thing");
 
             var result = option.Parse("-x none-of-those");
 
@@ -41,7 +41,7 @@ public void When_an_option_accepts_only_specific_arguments_but_a_wrong_one_is_su
         public void When_an_option_has_en_error_then_the_error_has_a_reference_to_the_option()
         {
             var option = new Option<string>("-x")
-                .FromAmong("this", "that");
+                .AcceptOnlyFromAmong("this", "that");
 
             var result = option.Parse("-x something_else");
 
@@ -54,7 +54,7 @@ public void When_an_option_has_en_error_then_the_error_has_a_reference_to_the_op
         [Fact] // https://github.com/dotnet/command-line-api/issues/1475
         public void When_FromAmong_is_used_then_the_OptionResult_ErrorMessage_is_set()
         {
-            var option = new Option<string>("--opt").FromAmong("a", "b");
+            var option = new Option<string>("--opt").AcceptOnlyFromAmong("a", "b");
             var command = new Command("test") { option };
 
             var parseResult = command.Parse("test --opt c");
@@ -71,7 +71,7 @@ public void When_FromAmong_is_used_then_the_OptionResult_ErrorMessage_is_set()
         [Fact] // https://github.com/dotnet/command-line-api/issues/1475
         public void When_FromAmong_is_used_then_the_ArgumentResult_ErrorMessage_is_set()
         {
-            var option = new Argument<string>().FromAmong("a", "b");
+            var option = new Argument<string>().AcceptOnlyFromAmong("a", "b");
             var command = new Command("test") { option };
 
             var parseResult = command.Parse("test c");
@@ -90,8 +90,8 @@ public void When_FromAmong_is_used_for_multiple_arguments_and_valid_input_is_pro
         {
             var command = new Command("set")
             {
-                new Argument<string>("key").FromAmong("key1", "key2"),
-                new Argument<string>("value").FromAmong("value1", "value2")
+                new Argument<string>("key").AcceptOnlyFromAmong("key1", "key2"),
+                new Argument<string>("value").AcceptOnlyFromAmong("value1", "value2")
             };
 
             var result = command.Parse("set key1 value1");
@@ -104,8 +104,8 @@ public void When_FromAmong_is_used_for_multiple_arguments_and_invalid_input_is_p
         {
             var command = new Command("set")
             {
-                new Argument<string>("key").FromAmong("key1", "key2"),
-                new Argument<string>("value").FromAmong("value1", "value2")
+                new Argument<string>("key").AcceptOnlyFromAmong("key1", "key2"),
+                new Argument<string>("value").AcceptOnlyFromAmong("value1", "value2")
             };
 
             var result = command.Parse("set not-key1 value1");
@@ -124,8 +124,8 @@ public void When_FromAmong_is_used_for_multiple_arguments_and_invalid_input_is_p
         {
             var command = new Command("set")
             {
-                new Argument<string>("key").FromAmong("key1", "key2"),
-                new Argument<string>("value").FromAmong("value1", "value2")
+                new Argument<string>("key").AcceptOnlyFromAmong("key1", "key2"),
+                new Argument<string>("value").AcceptOnlyFromAmong("value1", "value2")
             };
 
             var result = command.Parse("set key1 not-value1");
@@ -531,7 +531,7 @@ public void LegalFilePathsOnly_rejects_command_arguments_containing_invalid_path
             {
                 var command = new Command("the-command")
                 {
-                    new Argument<string>().LegalFilePathsOnly()
+                    new Argument<string>().AcceptLegalFilePathsOnly()
                 };
 
                 var invalidCharacter = Path.GetInvalidPathChars().First(c => c != '"');
@@ -551,7 +551,7 @@ public void LegalFilePathsOnly_rejects_option_arguments_containing_invalid_path_
             {
                 var command = new Command("the-command")
                 {
-                    new Option<string>("-x").LegalFilePathsOnly()
+                    new Option<string>("-x").AcceptLegalFilePathsOnly()
                 };
 
                 var invalidCharacter = Path.GetInvalidPathChars().First(c => c != '"');
@@ -571,7 +571,7 @@ public void LegalFilePathsOnly_accepts_command_arguments_containing_valid_path_c
             {
                 var command = new Command("the-command")
                 {
-                    new Argument<string[]>().LegalFilePathsOnly()
+                    new Argument<string[]>().AcceptLegalFilePathsOnly()
                 };
 
                 var validPathName = Directory.GetCurrentDirectory();
@@ -587,7 +587,7 @@ public void LegalFilePathsOnly_accepts_option_arguments_containing_valid_path_ch
             {
                 var command = new Command("the-command")
                 {
-                    new Option<string[]>("-x").LegalFilePathsOnly()
+                    new Option<string[]>("-x").AcceptLegalFilePathsOnly()
                 };
 
                 var validPathName = Directory.GetCurrentDirectory();
@@ -606,7 +606,7 @@ public void LegalFileNamesOnly_rejects_command_arguments_containing_invalid_file
             {
                 var command = new Command("the-command")
                 {
-                    new Argument<string>().LegalFileNamesOnly()
+                    new Argument<string>().AcceptLegalFileNamesOnly()
                 };
 
                 var invalidCharacter = Path.GetInvalidFileNameChars().First(c => c != '"');
@@ -626,7 +626,7 @@ public void LegalFileNamesOnly_rejects_option_arguments_containing_invalid_file_
             {
                 var command = new Command("the-command")
                 {
-                    new Option<string>("-x").LegalFileNamesOnly()
+                    new Option<string>("-x").AcceptLegalFileNamesOnly()
                 };
 
                 var invalidCharacter = Path.GetInvalidFileNameChars().First(c => c != '"');
@@ -646,7 +646,7 @@ public void LegalFileNamesOnly_accepts_command_arguments_containing_valid_file_n
             {
                 var command = new Command("the-command")
                 {
-                    new Argument<string[]>().LegalFileNamesOnly()
+                    new Argument<string[]>().AcceptLegalFileNamesOnly()
                 };
 
                 var validFileName = Path.GetFileName(Directory.GetCurrentDirectory());
@@ -662,7 +662,7 @@ public void LegalFileNamesOnly_accepts_option_arguments_containing_valid_file_na
             {
                 var command = new Command("the-command")
                 {
-                    new Option<string[]>("-x").LegalFileNamesOnly()
+                    new Option<string[]>("-x").AcceptLegalFileNamesOnly()
                 };
 
                 var validFileName = Path.GetFileName(Directory.GetCurrentDirectory());
@@ -681,7 +681,7 @@ public void A_command_argument_can_be_invalid_based_on_file_existence()
             {
                 var command = new Command("move")
                 {
-                    new Argument<FileInfo>("to").ExistingOnly()
+                    new Argument<FileInfo>("to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -700,7 +700,7 @@ public void An_option_argument_can_be_invalid_based_on_file_existence()
             {
                 var command = new Command("move")
                 {
-                    new Option<FileInfo>("--to").ExistingOnly()
+                    new Option<FileInfo>("--to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -719,7 +719,7 @@ public void A_command_argument_can_be_invalid_based_on_directory_existence()
             {
                 var command = new Command("move")
                 {
-                    new Argument<DirectoryInfo>("to").ExistingOnly()
+                    new Argument<DirectoryInfo>("to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -738,7 +738,7 @@ public void An_option_argument_can_be_invalid_based_on_directory_existence()
             {
                 var command = new Command("move")
                 {
-                    new Option<DirectoryInfo>("--to").ExistingOnly()
+                    new Option<DirectoryInfo>("--to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -757,7 +757,7 @@ public void A_command_argument_can_be_invalid_based_on_file_or_directory_existen
             {
                 var command = new Command("move")
                 {
-                    new Argument<FileSystemInfo>().ExistingOnly()
+                    new Argument<FileSystemInfo>().AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -776,7 +776,7 @@ public void An_option_argument_can_be_invalid_based_on_file_or_directory_existen
             {
                 var command = new Command("move")
                 {
-                    new Option<FileSystemInfo>("--to").ExistingOnly()
+                    new Option<FileSystemInfo>("--to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -795,7 +795,7 @@ public void A_command_argument_with_multiple_files_can_be_invalid_based_on_file_
             {
                 var command = new Command("move")
                 {
-                    new Argument<IEnumerable<FileInfo>>("to").ExistingOnly()
+                    new Argument<IEnumerable<FileInfo>>("to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -814,7 +814,7 @@ public void An_option_argument_with_multiple_files_can_be_invalid_based_on_file_
             {
                 var command = new Command("move")
                 {
-                    new Option<IEnumerable<FileInfo>>("--to").ExistingOnly()
+                    new Option<IEnumerable<FileInfo>>("--to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -833,7 +833,7 @@ public void A_command_argument_with_multiple_directories_can_be_invalid_based_on
             {
                 var command = new Command("move")
                 {
-                    new Argument<List<DirectoryInfo>>("to").ExistingOnly()
+                    new Argument<List<DirectoryInfo>>("to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -852,7 +852,7 @@ public void An_option_argument_with_multiple_directories_can_be_invalid_based_on
             {
                 var command = new Command("move")
                 {
-                    new Option<DirectoryInfo[]>("--to").ExistingOnly()
+                    new Option<DirectoryInfo[]>("--to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -874,7 +874,7 @@ public void A_command_argument_with_multiple_FileSystemInfos_can_be_invalid_base
                     new Argument<FileSystemInfo[]>("to")
                     {
                         Arity = ArgumentArity.ZeroOrMore
-                    }.ExistingOnly(),
+                    }.AcceptExistingOnly(),
                     new Option<string>("--to")
                 };
 
@@ -892,7 +892,7 @@ public void An_option_argument_with_multiple_FileSystemInfos_can_be_invalid_base
             {
                 var command = new Command("move")
                 {
-                    new Option<FileSystemInfo[]>("--to").ExistingOnly()
+                    new Option<FileSystemInfo[]>("--to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -911,7 +911,7 @@ public void A_command_argument_with_multiple_FileSystemInfos_can_be_invalid_base
             {
                 var command = new Command("move")
                 {
-                    new Argument<FileSystemInfo>("to").ExistingOnly()
+                    new Argument<FileSystemInfo>("to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -930,7 +930,7 @@ public void An_option_argument_with_multiple_FileSystemInfos_can_be_invalid_base
             {
                 var command = new Command("move")
                 {
-                    new Option<FileSystemInfo[]>("--to").ExistingOnly()
+                    new Option<FileSystemInfo[]>("--to").AcceptExistingOnly()
                 };
 
                 var path = NonexistentPath();
@@ -949,7 +949,7 @@ public void Command_argument_does_not_return_errors_when_file_exists()
             {
                 var command = new Command("move")
                 {
-                    new Argument<FileInfo>().ExistingOnly()
+                    new Argument<FileInfo>().AcceptExistingOnly()
                 };
 
                 var path = ExistingFile();
@@ -963,7 +963,7 @@ public void Option_argument_does_not_return_errors_when_file_exists()
             {
                 var command = new Command("move")
                 {
-                    new Option<FileInfo>("--to").ExistingOnly()
+                    new Option<FileInfo>("--to").AcceptExistingOnly()
                 };
 
                 var path = ExistingFile();
@@ -977,7 +977,7 @@ public void Command_argument_does_not_return_errors_when_Directory_exists()
             {
                 var command = new Command("move")
                 {
-                    new Argument<DirectoryInfo>().ExistingOnly()
+                    new Argument<DirectoryInfo>().AcceptExistingOnly()
                 };
 
                 var path = ExistingDirectory();
@@ -991,7 +991,7 @@ public void Option_argument_does_not_return_errors_when_Directory_exists()
             {
                 var command = new Command("move")
                 {
-                    new Option<DirectoryInfo>("--to").ExistingOnly()
+                    new Option<DirectoryInfo>("--to").AcceptExistingOnly()
                 };
 
                 var path = ExistingDirectory();
diff --git a/src/System.CommandLine.Tests/TestApps/Trimming/Program.cs b/src/System.CommandLine.Tests/TestApps/Trimming/Program.cs
index 40f6f6e3b3..a41990eaaa 100644
--- a/src/System.CommandLine.Tests/TestApps/Trimming/Program.cs
+++ b/src/System.CommandLine.Tests/TestApps/Trimming/Program.cs
@@ -1,7 +1,7 @@
 using System.CommandLine;
 using System.CommandLine.Invocation;
 
-var fileArgument = new Argument<FileInfo>().LegalFileNamesOnly();
+var fileArgument = new Argument<FileInfo>().AcceptLegalFileNamesOnly();
 
 var command = new RootCommand
 {
diff --git a/src/System.CommandLine/Argument.cs b/src/System.CommandLine/Argument.cs
index 343c777742..e0c589509c 100644
--- a/src/System.CommandLine/Argument.cs
+++ b/src/System.CommandLine/Argument.cs
@@ -6,6 +6,7 @@
 using System.CommandLine.Parsing;
 using System.CommandLine.Completions;
 using System.Linq;
+using System.IO;
 
 namespace System.CommandLine
 {
@@ -202,5 +203,124 @@ public override IEnumerable<CompletionItem> GetCompletions(CompletionContext con
 
         /// <inheritdoc />
         string IValueDescriptor.ValueName => Name;
+
+        /// <summary>
+        /// Adds completions for the argument.
+        /// </summary>
+        /// <param name="completions">The completions to add.</param>
+        /// <returns>The configured argument.</returns>
+        public Argument AddCompletions(params string[] completions)
+        {
+            Completions.Add(completions);
+            return this;
+        }
+
+        /// <summary>
+        /// Adds completions for the argument.
+        /// </summary>
+        /// <param name="completionsDelegate">A function that will be called to provide completions.</param>
+        /// <returns>The option being extended.</returns>
+        public Argument AddCompletions(Func<CompletionContext, IEnumerable<string>> completionsDelegate)
+        {
+            Completions.Add(completionsDelegate);
+            return this;
+        }
+
+        /// <summary>
+        /// Adds completions for the argument.
+        /// </summary>
+        /// <param name="completionsDelegate">A function that will be called to provide completions.</param>
+        /// <returns>The configured argument.</returns>
+        public Argument AddCompletions(Func<CompletionContext, IEnumerable<CompletionItem>> completionsDelegate)
+        {
+            Completions.Add(completionsDelegate);
+            return this;
+        }
+
+        /// <summary>
+        /// Configures the argument to accept only the specified values, and to suggest them as command line completions.
+        /// </summary>
+        /// <param name="values">The values that are allowed for the argument.</param>
+        /// <returns>The configured argument.</returns>
+        public Argument AcceptOnlyFromAmong(params string[] values)
+        {
+            AllowedValues?.Clear();
+            AddAllowedValues(values);
+            Completions.Clear();
+            Completions.Add(values);
+
+            return this;
+        }
+
+        /// <summary>
+        /// Configures the argument to accept only values representing legal file paths.
+        /// </summary>
+        /// <returns>The configured argument.</returns>
+        public Argument AcceptLegalFilePathsOnly()
+        {
+            var invalidPathChars = Path.GetInvalidPathChars();
+
+            AddValidator(result =>
+            {
+                for (var i = 0; i < result.Tokens.Count; i++)
+                {
+                    var token = result.Tokens[i];
+
+                    // File class no longer check invalid character
+                    // https://blogs.msdn.microsoft.com/jeremykuhne/2018/03/09/custom-directory-enumeration-in-net-core-2-1/
+                    var invalidCharactersIndex = token.Value.IndexOfAny(invalidPathChars);
+
+                    if (invalidCharactersIndex >= 0)
+                    {
+                        result.ErrorMessage = result.LocalizationResources.InvalidCharactersInPath(token.Value[invalidCharactersIndex]);
+                    }
+                }
+            });
+
+            return this;
+        }
+
+        /// <summary>
+        /// Configures the argument to accept only values representing legal file names.
+        /// </summary>
+        /// <remarks>A parse error will result, for example, if file path separators are found in the parsed value.</remarks>
+        /// <returns>The configured argument.</returns>
+        public Argument AcceptLegalFileNamesOnly()
+        {
+            var invalidFileNameChars = Path.GetInvalidFileNameChars();
+
+            AddValidator(result =>
+            {
+                for (var i = 0; i < result.Tokens.Count; i++)
+                {
+                    var token = result.Tokens[i];
+                    var invalidCharactersIndex = token.Value.IndexOfAny(invalidFileNameChars);
+
+                    if (invalidCharactersIndex >= 0)
+                    {
+                        result.ErrorMessage = result.LocalizationResources.InvalidCharactersInFileName(token.Value[invalidCharactersIndex]);
+                    }
+                }
+            });
+
+            return this;
+        }
+
+        /// <summary>
+        /// Parses a command line string value using the argument.
+        /// </summary>
+        /// <remarks>The command line string input will be split into tokens as if it had been passed on the command line.</remarks>
+        /// <param name="commandLine">A command line string to parse, which can include spaces and quotes equivalent to what can be entered into a terminal.</param>
+        /// <returns>A parse result describing the outcome of the parse operation.</returns>
+        public ParseResult Parse(string commandLine) =>
+            this.GetOrCreateDefaultSimpleParser().Parse(commandLine);
+
+        /// <summary>
+        /// Parses a command line string value using the argument.
+        /// </summary>
+        /// <param name="args">The string arguments to parse.</param>
+        /// <returns>A parse result describing the outcome of the parse operation.</returns>
+        public ParseResult Parse(string[] args) =>
+            this.GetOrCreateDefaultSimpleParser().Parse(args);
     }
 }
diff --git a/src/System.CommandLine/ArgumentExtensions.cs b/src/System.CommandLine/ArgumentExtensions.cs
deleted file mode 100644
index af69cba401..0000000000
--- a/src/System.CommandLine/ArgumentExtensions.cs
+++ /dev/null
@@ -1,227 +0,0 @@
-// Copyright (c) .NET Foundation and contributors. All rights reserved.
-// Licensed under the MIT license. See LICENSE file in the project root for full license information.
-
-using System.Collections.Generic;
-using System.CommandLine.Parsing;
-using System.CommandLine.Completions;
-using System.IO;
-
-namespace System.CommandLine
-{
-    /// <summary>
-    /// Provides extension methods for <see cref="Argument" />.
-    /// </summary>
-    public static class ArgumentExtensions
-    {
-        /// <summary>
-        /// Adds completions for an argument.
-        /// </summary>
-        /// <typeparam name="TArgument">The type of the argument.</typeparam>
-        /// <param name="argument">The argument for which to add completions.</param>
-        /// <param name="values">The completions to add.</param>
-        /// <returns>The configured argument.</returns>
-        public static TArgument AddCompletions<TArgument>(
-            this TArgument argument,
-            params string[] values)
-            where TArgument : Argument
-        {
-            argument.Completions.Add(values);
-
-            return argument;
-        }
-    
-        /// <summary>
-        /// Adds completions for an option.
-        /// </summary>
-        /// <typeparam name="TArgument">The type of the argument.</typeparam>
-        /// <param name="argument">The argument for which to add completions.</param>
-        /// <param name="complete">A function that will be called to provide completions.</param>
-        /// <returns>The option being extended.</returns>
-        public static TArgument AddCompletions<TArgument>(
-            this TArgument argument,
-            Func<CompletionContext, IEnumerable<string>> complete)
-            where TArgument : Argument
-        {
-            argument.Completions.Add(complete);
-
-            return argument;
-        }
-
-        /// <summary>
-        /// Adds completions for an argument.
-        /// </summary>
-        /// <typeparam name="TArgument">The type of the argument.</typeparam>
-        /// <param name="argument">The argument for which to add completions.</param>
-        /// <param name="complete">A function that will be called to provide completions.</param>
-        /// <returns>The configured argument.</returns>
-        public static TArgument AddCompletions<TArgument>(
-            this TArgument argument,
-            Func<CompletionContext, IEnumerable<CompletionItem>> complete)
-            where TArgument : Argument
-        {
-            argument.Completions.Add(complete);
-
-            return argument;
-        }
-
-        /// <summary>
-        /// Configures an argument to accept only the specified values, and to suggest them as command line completions.
-        /// </summary>
-        /// <param name="argument">The argument to configure.</param>
-        /// <param name="values">The values that are allowed for the argument.</param>
-        /// <typeparam name="TArgument">The type of the argument.</typeparam>
-        /// <returns>The configured argument.</returns>
-        public static TArgument FromAmong<TArgument>(
-            this TArgument argument,
-            params string[] values)
-            where TArgument : Argument
-        {
-            argument.AllowedValues?.Clear();
-            argument.AddAllowedValues(values);
-            argument.Completions.Clear();
-            argument.Completions.Add(values);
-
-            return argument;
-        }
-
-        /// <summary>
-        /// Configures an argument to accept only values corresponding to an existing file.
-        /// </summary>
-        /// <param name="argument">The argument to configure.</param>
-        /// <returns>The configured argument.</returns>
-        public static Argument<FileInfo> ExistingOnly(this Argument<FileInfo> argument)
-        {
-            argument.AddValidator(Validate.FileExists);
-            return argument;
-        }
-
-        /// <summary>
-        /// Configures an argument to accept only values corresponding to an existing directory.
-        /// </summary>
-        /// <param name="argument">The argument to configure.</param>
-        /// <returns>The configured argument.</returns>
-        public static Argument<DirectoryInfo> ExistingOnly(this Argument<DirectoryInfo> argument)
-        {
-            argument.AddValidator(Validate.DirectoryExists);
-            return argument;
-        }
-
-        /// <summary>
-        /// Configures an argument to accept only values corresponding to an existing file or directory.
-        /// </summary>
-        /// <param name="argument">The argument to configure.</param>
-        /// <returns>The configured argument.</returns>
-        public static Argument<FileSystemInfo> ExistingOnly(this Argument<FileSystemInfo> argument)
-        {
-            argument.AddValidator(Validate.FileOrDirectoryExists);
-            return argument;
-        }
-
-        /// <summary>
-        /// Configures an argument to accept only values corresponding to a existing files or directories.
-        /// </summary>
-        /// <param name="argument">The argument to configure.</param>
-        /// <returns>The configured argument.</returns>
-        public static Argument<T> ExistingOnly<T>(this Argument<T> argument)
-            where T : IEnumerable<FileSystemInfo>
-        {
-            if (typeof(IEnumerable<FileInfo>).IsAssignableFrom(typeof(T)))
-            {
-                argument.AddValidator(Validate.FileExists);
-            }
-            else if (typeof(IEnumerable<DirectoryInfo>).IsAssignableFrom(typeof(T)))
-            {
-                argument.AddValidator(Validate.DirectoryExists);
-            }
-            else
-            {
-                argument.AddValidator(Validate.FileOrDirectoryExists);
-            }
-
-            return argument;
-        }
-
-        /// <summary>
-        /// Configures an argument to accept only values representing legal file paths.
-        /// </summary>
-        /// <param name="argument">The argument to configure.</param>
-        /// <returns>The configured argument.</returns>
-        public static TArgument LegalFilePathsOnly<TArgument>(
-            this TArgument argument)
-            where TArgument : Argument
-        {
-            var invalidPathChars = Path.GetInvalidPathChars();
-
-            argument.AddValidator(result =>
-            {
-                for (var i = 0; i < result.Tokens.Count; i++)
-                {
-                    var token = result.Tokens[i];
-
-                    // File class no longer check invalid character
-                    // https://blogs.msdn.microsoft.com/jeremykuhne/2018/03/09/custom-directory-enumeration-in-net-core-2-1/
-                    var invalidCharactersIndex = token.Value.IndexOfAny(invalidPathChars);
-
-                    if (invalidCharactersIndex >= 0)
-                    {
-                        result.ErrorMessage = result.LocalizationResources.InvalidCharactersInPath(token.Value[invalidCharactersIndex]);
-                    }
-                }
-            });
-
-            return argument;
-        }
-
-        /// <summary>
-        /// Configures an argument to accept only values representing legal file names.
-        /// </summary>
-        /// <remarks>A parse error will result, for example, if file path separators are found in the parsed value.</remarks>
-        /// <param name="argument">The argument to configure.</param>
-        /// <returns>The configured argument.</returns>
-        public static TArgument LegalFileNamesOnly<TArgument>(
-            this TArgument argument)
-            where TArgument : Argument
-        {
-            var invalidFileNameChars = Path.GetInvalidFileNameChars();
-
-            argument.AddValidator(result =>
-            {
-                for (var i = 0; i < result.Tokens.Count; i++)
-                {
-                    var token = result.Tokens[i];
-                    var invalidCharactersIndex = token.Value.IndexOfAny(invalidFileNameChars);
-
-                    if (invalidCharactersIndex >= 0)
-                    {
-                        result.ErrorMessage =  result.LocalizationResources.InvalidCharactersInFileName(token.Value[invalidCharactersIndex]);
-                    }
-                }
-            });
-
-            return argument;
-        }
-        
-        /// <summary>
-        /// Parses a command line string value using an argument.
-        /// </summary>
-        /// <remarks>The command line string input will be split into tokens as if it had been passed on the command line.</remarks>
-        /// <param name="argument">The argument to use to parse the command line input.</param>
-        /// <param name="commandLine">A command line string to parse, which can include spaces and quotes equivalent to what can be entered into a terminal.</param>
-        /// <returns>A parse result describing the outcome of the parse operation.</returns>
-        public static ParseResult Parse(
-            this Argument argument,
-            string commandLine) =>
-            argument.GetOrCreateDefaultSimpleParser().Parse(commandLine);
-
-        /// <summary>
-        /// Parses a command line string value using an argument.
-        /// </summary>
-        /// <param name="argument">The argument to use to parse the command line input.</param>
-        /// <param name="args">The string arguments to parse.</param>
-        /// <returns>A parse result describing the outcome of the parse operation.</returns>
-        public static ParseResult Parse(
-            this Argument argument,
-            string[] args) =>
-            argument.GetOrCreateDefaultSimpleParser().Parse(args);
-    }
-}
diff --git a/src/System.CommandLine/ArgumentValidation.cs b/src/System.CommandLine/ArgumentValidation.cs
new file mode 100644
index 0000000000..37282c871a
--- /dev/null
+++ b/src/System.CommandLine/ArgumentValidation.cs
@@ -0,0 +1,71 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Collections.Generic;
+using System.IO;
+
+namespace System.CommandLine
+{
+    /// <summary>
+    /// Provides extension methods for <see cref="Argument" />.
+    /// </summary>
+    public static class ArgumentValidation
+    {
+        /// <summary>
+        /// Configures an argument to accept only values corresponding to an existing file.
+        /// </summary>
+        /// <param name="argument">The argument to configure.</param>
+        /// <returns>The configured argument.</returns>
+        public static Argument<FileInfo> AcceptExistingOnly(this Argument<FileInfo> argument)
+        {
+            argument.AddValidator(Validate.FileExists);
+            return argument;
+        }
+
+        /// <summary>
+        /// Configures an argument to accept only values corresponding to an existing directory.
+        /// </summary>
+        /// <param name="argument">The argument to configure.</param>
+        /// <returns>The configured argument.</returns>
+        public static Argument<DirectoryInfo> AcceptExistingOnly(this Argument<DirectoryInfo> argument)
+        {
+            argument.AddValidator(Validate.DirectoryExists);
+            return argument;
+        }
+
+        /// <summary>
+        /// Configures an argument to accept only values corresponding to an existing file or directory.
+        /// </summary>
+        /// <param name="argument">The argument to configure.</param>
+        /// <returns>The configured argument.</returns>
+        public static Argument<FileSystemInfo> AcceptExistingOnly(this Argument<FileSystemInfo> argument)
+        {
+            argument.AddValidator(Validate.FileOrDirectoryExists);
+            return argument;
+        }
+
+        /// <summary>
+        /// Configures an argument to accept only values corresponding to a existing files or directories.
+        /// </summary>
+        /// <param name="argument">The argument to configure.</param>
+        /// <returns>The configured argument.</returns>
+        public static Argument<T> AcceptExistingOnly<T>(this Argument<T> argument)
+            where T : IEnumerable<FileSystemInfo>
+        {
+            if (typeof(IEnumerable<FileInfo>).IsAssignableFrom(typeof(T)))
+            {
+                argument.AddValidator(Validate.FileExists);
+            }
+            else if (typeof(IEnumerable<DirectoryInfo>).IsAssignableFrom(typeof(T)))
+            {
+                argument.AddValidator(Validate.DirectoryExists);
+            }
+            else
+            {
+                argument.AddValidator(Validate.FileOrDirectoryExists);
+            }
+
+            return argument;
+        }
+    }
+}
diff --git a/src/System.CommandLine/CompletionSourceExtensions.cs b/src/System.CommandLine/CompletionSourceExtensions.cs
index 4456e9d424..bfe34fd2a4 100644
--- a/src/System.CommandLine/CompletionSourceExtensions.cs
+++ b/src/System.CommandLine/CompletionSourceExtensions.cs
@@ -16,22 +16,22 @@ public static class CompletionSourceExtensions
         /// Adds a completion source using a delegate.
         /// </summary>
         /// <param name="completionSources">The list of completion sources to add to.</param>
-        /// <param name="complete">The delegate to be called when calculating completions.</param>
+        /// <param name="completionsDelegate">The delegate to be called when calculating completions.</param>
         public static void Add(
             this ICollection<Func<CompletionContext, IEnumerable<CompletionItem>>> completionSources,
-            Func<CompletionContext, IEnumerable<string>> complete)
+            Func<CompletionContext, IEnumerable<string>> completionsDelegate)
         {
             if (completionSources is null)
             {
                 throw new ArgumentNullException(nameof(completionSources));
             }
 
-            if (complete is null)
+            if (completionsDelegate is null)
             {
-                throw new ArgumentNullException(nameof(complete));
+                throw new ArgumentNullException(nameof(completionsDelegate));
             }
 
-            completionSources.Add(context => complete(context).Select(value => new CompletionItem(value)));
+            completionSources.Add(context => completionsDelegate(context).Select(value => new CompletionItem(value)));
         }
 
         /// <summary>
diff --git a/src/System.CommandLine/Option.cs b/src/System.CommandLine/Option.cs
index 8f24e496d3..e146ea0ea0 100644
--- a/src/System.CommandLine/Option.cs
+++ b/src/System.CommandLine/Option.cs
@@ -234,5 +234,91 @@ public override IEnumerable<CompletionItem> GetCompletions(CompletionContext con
                    .OrderBy(item => item.SortText.IndexOfCaseInsensitive(context.WordToComplete))
                    .ThenBy(symbol => symbol.Label, StringComparer.OrdinalIgnoreCase);
         }
+
+        /// <summary>
+        /// Configures the option to accept only the specified values, and to suggest them as command line completions.
+        /// </summary>
+        /// <param name="values">The values that are allowed for the option.</param>
+        /// <returns>The configured option.</returns>
+        public Option AcceptOnlyFromAmong(params string[] values)
+        {
+            Argument.AllowedValues?.Clear();
+            Argument.AddAllowedValues(values);
+            Argument.Completions.Clear();
+            Argument.Completions.Add(values);
+
+            return this;
+        }
+
+        /// <summary>
+        /// Adds completions for the option.
+        /// </summary>
+        /// <param name="completions">The completions to add.</param>
+        /// <returns>The configured option.</returns>
+        public Option AddCompletions(params string[] completions)
+        {
+            Argument.Completions.Add(completions);
+            return this;
+        }
+
+        /// <summary>
+        /// Adds completions for the option.
+        /// </summary>
+        /// <param name="completionsDelegate">A function that will be called to provide completions.</param>
+        /// <returns>The configured option.</returns>
+        public Option AddCompletions(Func<CompletionContext, IEnumerable<string>> completionsDelegate)
+        {
+            Argument.Completions.Add(completionsDelegate);
+            return this;
+        }
+
+        /// <summary>
+        /// Adds completions for the option.
+        /// </summary>
+        /// <param name="completionsDelegate">A function that will be called to provide completions.</param>
+        /// <returns>The configured option.</returns>
+        public Option AddCompletions(Func<CompletionContext, IEnumerable<CompletionItem>> completionsDelegate)
+        {
+            Argument.Completions.Add(completionsDelegate);
+            return this;
+        }
+
+        /// <summary>
+        /// Configures the option to accept only values representing legal file paths.
+        /// </summary>
+        /// <returns>The configured option.</returns>
+        public Option AcceptLegalFilePathsOnly()
+        {
+            Argument.AcceptLegalFilePathsOnly();
+            return this;
+        }
+
+        /// <summary>
+        /// Configures the option to accept only values representing legal file names.
+        /// </summary>
+        /// <remarks>A parse error will result, for example, if file path separators are found in the parsed value.</remarks>
+        /// <returns>The configured option.</returns>
+        public Option AcceptLegalFileNamesOnly()
+        {
+            Argument.AcceptLegalFileNamesOnly();
+            return this;
+        }
+
+        /// <summary>
+        /// Parses a command line string value using the option.
+        /// </summary>
+        /// <remarks>The command line string input will be split into tokens as if it had been passed on the command line.</remarks>
+        /// <param name="commandLine">A command line string to parse, which can include spaces and quotes equivalent to what can be entered into a terminal.</param>
+        /// <returns>A parse result describing the outcome of the parse operation.</returns>
+        public ParseResult Parse(string commandLine) =>
+            this.GetOrCreateDefaultSimpleParser().Parse(commandLine);
+
+        /// <summary>
+        /// Parses a command line string value using the option.
+        /// </summary>
+        /// <param name="args">The string options to parse.</param>
+        /// <returns>A parse result describing the outcome of the parse operation.</returns>
+        public ParseResult Parse(string[] args) =>
+            this.GetOrCreateDefaultSimpleParser().Parse(args);
     }
 }
diff --git a/src/System.CommandLine/OptionExtensions.cs b/src/System.CommandLine/OptionExtensions.cs
deleted file mode 100644
index 8eb72c1288..0000000000
--- a/src/System.CommandLine/OptionExtensions.cs
+++ /dev/null
@@ -1,188 +0,0 @@
-// Copyright (c) .NET Foundation and contributors. All rights reserved.
-// Licensed under the MIT license. See LICENSE file in the project root for full license information.
-
-using System.Collections.Generic;
-using System.CommandLine.Parsing;
-using System.CommandLine.Completions;
-using System.IO;
-
-namespace System.CommandLine
-{
-    /// <summary>
-    /// Provides extension methods for <see cref="Option" />.
-    /// </summary>
-    public static class OptionExtensions
-    {
-        /// <summary>
-        /// Configures an option to accept only the specified values, and to suggest them as command line completions.
-        /// </summary>
-        /// <param name="option">The option to configure.</param>
-        /// <param name="values">The values that are allowed for the option.</param>
-        /// <typeparam name="TOption">The type of the option's parsed value.</typeparam>
-        /// <returns>The configured argument.</returns>
-        public static TOption FromAmong<TOption>(
-            this TOption option,
-            params string[] values)
-            where TOption : Option
-        {
-            option.Argument.AllowedValues?.Clear();
-            option.Argument.AddAllowedValues(values);
-            option.Argument.Completions.Clear();
-            option.Argument.Completions.Add(values);
-
-            return option;
-        }
-
-        /// <summary>
-        /// Adds completions for an option.
-        /// </summary>
-        /// <typeparam name="TOption">The type of the <see cref="Option" />.</typeparam>
-        /// <param name="option">The option for which to add completions.</param>
-        /// <param name="values">The completions to add.</param>
-        /// <returns>The option being extended.</returns>
-        public static TOption AddCompletions<TOption>(
-            this TOption option,
-            params string[] values)
-            where TOption : Option
-        {
-            option.Argument.Completions.Add(values);
-
-            return option;
-        }
-        
-        /// <summary>
-        /// Adds completions for an option.
-        /// </summary>
-        /// <typeparam name="TOption">The type of the option.</typeparam>
-        /// <param name="option">The option for which to add completions.</param>
-        /// <param name="complete">A function that will be called to provide completions.</param>
-        /// <returns>The option being extended.</returns>
-        public static TOption AddCompletions<TOption>(
-            this TOption option,
-            Func<CompletionContext, IEnumerable<string>> complete)
-            where TOption : Option
-        {
-            option.Argument.Completions.Add(complete);
-
-            return option;
-        }
-   
-        /// <summary>
-        /// Adds completions for an option.
-        /// </summary>
-        /// <typeparam name="TOption">The type of the option.</typeparam>
-        /// <param name="option">The option for which to add completions.</param>
-        /// <param name="complete">A function that will be called to provide completions.</param>
-        /// <returns>The option being extended.</returns>
-        public static TOption AddCompletions<TOption>(
-            this TOption option,
-            Func<CompletionContext, IEnumerable<CompletionItem>> complete)
-            where TOption : Option
-        {
-            option.Argument.Completions.Add(complete);
-
-            return option;
-        }
-
-        /// <summary>
-        /// Configures an option to accept only values corresponding to an existing file.
-        /// </summary>
-        /// <param name="option">The option to configure.</param>
-        /// <returns>The option being extended.</returns>
-        public static Option<FileInfo> ExistingOnly(this Option<FileInfo> option)
-        {
-            option.Argument.AddValidator(Validate.FileExists);
-            return option;
-        }
-
-        /// <summary>
-        /// Configures an option to accept only values corresponding to an existing directory.
-        /// </summary>
-        /// <param name="option">The option to configure.</param>
-        /// <returns>The option being extended.</returns>
-        public static Option<DirectoryInfo> ExistingOnly(this Option<DirectoryInfo> option)
-        {
-            option.Argument.AddValidator(Validate.DirectoryExists);
-            return option;
-        }
-
-        /// <summary>
-        /// Configures an option to accept only values corresponding to an existing file or directory.
-        /// </summary>
-        /// <param name="option">The option to configure.</param>
-        /// <returns>The option being extended.</returns>
-        public static Option<FileSystemInfo> ExistingOnly(this Option<FileSystemInfo> option)
-        {
-            option.Argument.AddValidator(Validate.FileOrDirectoryExists);
-            return option;
-        }
-
-        /// <summary>
-        /// Configures an option to accept only values corresponding to a existing files or directories.
-        /// </summary>
-        /// <param name="option">The option to configure.</param>
-        /// <returns>The option being extended.</returns>
-        public static Option<T> ExistingOnly<T>(this Option<T> option)
-            where T : IEnumerable<FileSystemInfo>
-        {
-            if (option.Argument is Argument<T> arg)
-            {
-                arg.ExistingOnly();
-            }
-
-            return option;
-        }
-
-        /// <summary>
-        /// Configures an option to accept only values representing legal file paths.
-        /// </summary>
-        /// <param name="option">The option to configure.</param>
-        /// <returns>The option being extended.</returns>
-        public static TOption LegalFilePathsOnly<TOption>(
-            this TOption option)
-            where TOption : Option
-        {
-            option.Argument.LegalFilePathsOnly();
-
-            return option;
-        }
-
-        /// <summary>
-        /// Configures an option to accept only values representing legal file names.
-        /// </summary>
-        /// <remarks>A parse error will result, for example, if file path separators are found in the parsed value.</remarks>
-        /// <param name="option">The option to configure.</param>
-        /// <returns>The option being extended.</returns>
-        public static TOption LegalFileNamesOnly<TOption>(
-            this TOption option)
-            where TOption : Option
-        {
-            option.Argument.LegalFileNamesOnly();
-
-            return option;
-        }
-
-        /// <summary>
-        /// Parses a command line string value using an option.
-        /// </summary>
-        /// <remarks>The command line string input will be split into tokens as if it had been passed on the command line.</remarks>
-        /// <param name="option">The option to use to parse the command line input.</param>
-        /// <param name="commandLine">A command line string to parse, which can include spaces and quotes equivalent to what can be entered into a terminal.</param>
-        /// <returns>A parse result describing the outcome of the parse operation.</returns>
-        public static ParseResult Parse(
-            this Option option,
-            string commandLine) =>
-            option.GetOrCreateDefaultSimpleParser().Parse(commandLine);
-
-        /// <summary>
-        /// Parses a command line string value using an option.
-        /// </summary>
-        /// <param name="option">The option to use to parse the command line input.</param>
-        /// <param name="args">The string options to parse.</param>
-        /// <returns>A parse result describing the outcome of the parse operation.</returns>
-        public static ParseResult Parse(
-            this Option option,
-            string[] args) =>
-            option.GetOrCreateDefaultSimpleParser().Parse(args);
-    }
-}
\ No newline at end of file
diff --git a/src/System.CommandLine/OptionValidation.cs b/src/System.CommandLine/OptionValidation.cs
new file mode 100644
index 0000000000..4637028c08
--- /dev/null
+++ b/src/System.CommandLine/OptionValidation.cs
@@ -0,0 +1,63 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Collections.Generic;
+using System.IO;
+
+namespace System.CommandLine
+{
+    /// <summary>
+    /// Provides extension methods for <see cref="Option" />.
+    /// </summary>
+    public static class OptionValidation
+    {
+        /// <summary>
+        /// Configures an option to accept only values corresponding to an existing file.
+        /// </summary>
+        /// <param name="option">The option to configure.</param>
+        /// <returns>The option being extended.</returns>
+        public static Option<FileInfo> AcceptExistingOnly(this Option<FileInfo> option)
+        {
+            option.Argument.AddValidator(Validate.FileExists);
+            return option;
+        }
+
+        /// <summary>
+        /// Configures an option to accept only values corresponding to an existing directory.
+        /// </summary>
+        /// <param name="option">The option to configure.</param>
+        /// <returns>The option being extended.</returns>
+        public static Option<DirectoryInfo> AcceptExistingOnly(this Option<DirectoryInfo> option)
+        {
+            option.Argument.AddValidator(Validate.DirectoryExists);
+            return option;
+        }
+
+        /// <summary>
+        /// Configures an option to accept only values corresponding to an existing file or directory.
+        /// </summary>
+        /// <param name="option">The option to configure.</param>
+        /// <returns>The option being extended.</returns>
+        public static Option<FileSystemInfo> AcceptExistingOnly(this Option<FileSystemInfo> option)
+        {
+            option.Argument.AddValidator(Validate.FileOrDirectoryExists);
+            return option;
+        }
+
+        /// <summary>
+        /// Configures an option to accept only values corresponding to a existing files or directories.
+        /// </summary>
+        /// <param name="option">The option to configure.</param>
+        /// <returns>The option being extended.</returns>
+        public static Option<T> AcceptExistingOnly<T>(this Option<T> option)
+            where T : IEnumerable<FileSystemInfo>
+        {
+            if (option.Argument is Argument<T> arg)
+            {
+                arg.AcceptExistingOnly();
+            }
+
+            return option;
+        }
+    }
+}
\ No newline at end of file