diff --git a/lib/instructor.ex b/lib/instructor.ex
index 70178e9..e216327 100644
--- a/lib/instructor.ex
+++ b/lib/instructor.ex
@@ -34,6 +34,8 @@ defmodule Instructor do
     * `:mode` - The mode to use when parsing the response, :tools, :json, :md_json (defaults to `:tools`), generally speaking you don't need to change this unless you are not using OpenAI.
     * `:max_retries` - The maximum number of times to retry the LLM call if it fails, or does not pass validations.
                        (defaults to `0`)
+    * `:instructor_role` - The role to use in system messages. Defaults to `"system"`.
+                           Some models, such as OpenAI's o1 series, require the role to be `"developer"`.
 
   ## Examples
 
@@ -126,6 +128,7 @@ defmodule Instructor do
       params
       |> Keyword.put_new(:max_retries, 0)
       |> Keyword.put_new(:mode, :tools)
+      |> Keyword.put_new(:instructor_role, "system")
 
     is_stream = Keyword.get(params, :stream, false)
     response_model = Keyword.fetch!(params, :response_model)
@@ -453,7 +456,7 @@ defmodule Instructor do
                 reask_messages(raw_response, params, config) ++
                 [
                   %{
-                    role: "system",
+                    role: Keyword.get(params, :instructor_role, "system"),
                     content: """
                     The response did not pass validation. Please try again and fix the following validation errors:\n
 
@@ -513,7 +516,7 @@ defmodule Instructor do
           end
 
         sys_message = %{
-          role: "system",
+          role: Keyword.get(params, :instructor_role, "system"),
           content: """
           As a genius expert, your task is to understand the content and provide the parsed objects in json that match the following json_schema:\n
           #{json_schema}
diff --git a/lib/instructor/adapters/anthropic.ex b/lib/instructor/adapters/anthropic.ex
index 74191e9..115a82c 100644
--- a/lib/instructor/adapters/anthropic.ex
+++ b/lib/instructor/adapters/anthropic.ex
@@ -34,6 +34,7 @@ defmodule Instructor.Adapters.Anthropic do
     {_, params} = Keyword.pop(params, :response_model)
     {_, params} = Keyword.pop(params, :validation_context)
     {_, params} = Keyword.pop(params, :max_retries)
+    {_, params} = Keyword.pop(params, :instructor_role)
     {mode, params} = Keyword.pop(params, :mode)
     stream = Keyword.get(params, :stream, false)
     params = Enum.into(params, %{})
diff --git a/lib/instructor/adapters/gemini.ex b/lib/instructor/adapters/gemini.ex
index 66dc933..9c6ed66 100644
--- a/lib/instructor/adapters/gemini.ex
+++ b/lib/instructor/adapters/gemini.ex
@@ -42,6 +42,7 @@ defmodule Instructor.Adapters.Gemini do
     {_, params} = Keyword.pop(params, :response_model)
     {_, params} = Keyword.pop(params, :validation_context)
     {_, params} = Keyword.pop(params, :max_retries)
+    {_, params} = Keyword.pop(params, :instructor_role)
     {mode, params} = Keyword.pop(params, :mode)
     stream = Keyword.get(params, :stream, false)
     params = Enum.into(params, %{})
diff --git a/lib/instructor/adapters/openai.ex b/lib/instructor/adapters/openai.ex
index c4db50c..f0e4c44 100644
--- a/lib/instructor/adapters/openai.ex
+++ b/lib/instructor/adapters/openai.ex
@@ -16,6 +16,7 @@ defmodule Instructor.Adapters.OpenAI do
     {_, params} = Keyword.pop(params, :response_model)
     {_, params} = Keyword.pop(params, :validation_context)
     {_, params} = Keyword.pop(params, :max_retries)
+    {_, params} = Keyword.pop(params, :instructor_role)
     {mode, params} = Keyword.pop(params, :mode)
     stream = Keyword.get(params, :stream, false)
     params = Enum.into(params, %{})
diff --git a/lib/instructor/validator.ex b/lib/instructor/validator.ex
index c81b96b..8cade6a 100644
--- a/lib/instructor/validator.ex
+++ b/lib/instructor/validator.ex
@@ -104,7 +104,7 @@ defmodule Instructor.Validator do
           response_model: Validation,
           messages: [
             %{
-              role: "system",
+              role: Keyword.get(opts, :instructor_role, "system"),
               content: """
               You are a world class validation model. Capable to determine if the following value is valid for the statement, if it is not, explain why.
               """