diff --git a/railties/CHANGELOG b/railties/CHANGELOG
index 6df7c568dc..3a276d5aad 100644
--- a/railties/CHANGELOG
+++ b/railties/CHANGELOG
@@ -1,5 +1,7 @@
 *Edge*
 
+* Added config.threadsafe! to toggle allow concurrency settings and disable the dependency loader [Josh Peek]
+
 * Turn cache_classes on by default [Josh Peek]
 
 * Added configurable eager load paths. Defaults to app/models, app/controllers, and app/helpers [Josh Peek]
diff --git a/railties/environments/production.rb b/railties/environments/production.rb
index e915e8be73..ec5b7bc865 100644
--- a/railties/environments/production.rb
+++ b/railties/environments/production.rb
@@ -4,6 +4,9 @@
 # Code is not reloaded between requests
 config.cache_classes = true
 
+# Enable threaded mode
+# config.threadsafe!
+
 # Use a different logger for distributed setups
 # config.logger = SyslogLogger.new
 
diff --git a/railties/lib/initializer.rb b/railties/lib/initializer.rb
index e876481cf1..f8b3a78dff 100644
--- a/railties/lib/initializer.rb
+++ b/railties/lib/initializer.rb
@@ -768,6 +768,18 @@ Run `rake gems:install` to install the missing gems.
       ::RAILS_ROOT.replace @root_path
     end
 
+    # Enable threaded mode. Allows concurrent requests to controller actions and
+    # multiple database connections. Also disables automatic dependency loading
+    # after boot
+    def threadsafe!
+      self.cache_classes = true
+      self.dependency_loading = false
+      self.active_record.allow_concurrency = true
+      self.action_controller.allow_concurrency = true
+      self.to_prepare { Rails.cache.threadsafe! }
+      self
+    end
+
     # Loads and returns the contents of the #database_configuration_file. The
     # contents of the file are processed via ERB before being sent through
     # YAML::load.