diff --git a/lib/sendgrid.ex b/lib/sendgrid.ex
index 5269c81..7f8208d 100644
--- a/lib/sendgrid.ex
+++ b/lib/sendgrid.ex
@@ -62,9 +62,9 @@ defmodule SendGrid do
   * `:api_key` - API key to use with the request.
   * `:query` - Keyword list of query params to use with the request.
   """
-  @spec post(path :: String.t(), body :: map(), options :: options()) ::
+  @spec post(path :: String.t(), body :: Tesla.Env.body(), options :: options()) ::
           {:ok, Response.t()} | {:error, any()}
-  def post(path, body, opts \\ []) when is_map(body) and is_list(opts) do
+  def post(path, body, opts \\ []) when is_list(opts) do
     opts
     |> api_key()
     |> build_client()
@@ -80,9 +80,9 @@ defmodule SendGrid do
   * `:api_key` - API key to use with the request.
   * `:query` - Keyword list of query params to use with the request.
   """
-  @spec patch(path :: String.t(), body :: map(), options :: options()) ::
+  @spec patch(path :: String.t(), body :: Tesla.Env.body(), options :: options()) ::
           {:ok, Response.t()} | {:error, any()}
-  def patch(path, body, opts \\ []) when is_map(body) and is_list(opts) do
+  def patch(path, body, opts \\ []) when is_list(opts) do
     opts
     |> api_key()
     |> build_client()
diff --git a/lib/sendgrid/marketing_campaigns/contacts/lists.ex b/lib/sendgrid/marketing_campaigns/contacts/lists.ex
index bb21235..b961a63 100644
--- a/lib/sendgrid/marketing_campaigns/contacts/lists.ex
+++ b/lib/sendgrid/marketing_campaigns/contacts/lists.ex
@@ -82,6 +82,21 @@ defmodule SendGrid.Contacts.Lists do
     end
   end
 
+  @doc """
+  Adds multiple recipients to an email list.
+
+      :ok = add_recipients(123, ["recipient_id_1", "recipient_id_2"])
+
+  """
+  @spec add_recipients(integer(), [String.t()], [SendGrid.api_key()]) :: :ok | {:error, any()}
+  def add_recipients(list_id, recipient_ids, opts \\ []) when is_list(recipient_ids) do
+    url = "#{@base_api_url}/#{list_id}/recipients"
+
+    with {:ok, %{status: 201}} <- SendGrid.post(url, recipient_ids, opts) do
+      :ok
+    end
+  end
+
   @doc """
   Deletes a recipient from an email list.
 
diff --git a/lib/sendgrid/marketing_campaigns/contacts/recipients.ex b/lib/sendgrid/marketing_campaigns/contacts/recipients.ex
index 0f3e1b1..3595c08 100644
--- a/lib/sendgrid/marketing_campaigns/contacts/recipients.ex
+++ b/lib/sendgrid/marketing_campaigns/contacts/recipients.ex
@@ -36,6 +36,29 @@ defmodule SendGrid.Contacts.Recipients do
     end
   end
 
+  @doc """
+  Adds or updates multiple recipients in contacts list.
+  Recipients param must be in format required by Sendgrid:
+    [
+      %{
+        "email" => "test@example.com",
+        "name"  => "John Doe",
+        etc...
+      }
+    ]
+  """
+  @spec add_multiple([]) :: {:ok, [String.t]} | {:ok, map()} | {:error, list(String.t)}
+  def add_multiple(recipients) when is_list(recipients) do
+    with {:ok, response} <- SendGrid.patch(@base_api_url, recipients) do
+      handle_recipient_result(response)
+    end
+  end
+
+  # Handles the result when there are multiple persisted recipients.
+  defp handle_recipient_result(%{body: %{"persisted_recipients" => recipients} = body}) when is_list(recipients) and length(recipients) > 1 do
+    {:ok, body}
+  end
+
   # Handles the result when errors are present.
   defp handle_recipient_result(%{body: %{"error_count" => count} = body}) when count > 0 do
     errors = Enum.map(body["errors"], & &1["message"])