diff --git a/railties/guides/source/configuring.textile b/railties/guides/source/configuring.textile
index 4f7ac60b87..7e40cad040 100644
--- a/railties/guides/source/configuring.textile
+++ b/railties/guides/source/configuring.textile
@@ -316,6 +316,8 @@ h4. Configuring Active Support
 
 There are a few configuration options available in Active Support:
 
+* +config.active_support.bare+ enables or disables the loading of +active_support/all+ when booting Rails. Defaults to +nil+, which means +active_support/all+ is loaded.
+
 * +config.active_support.escape_html_entities_in_json+ enables or disables the escaping of HTML entities in JSON serialization. Defaults to +true+.
 
 * +config.active_support.use_standard_json_time_format+ enables or disables serializing dates to ISO 8601 format. Defaults to +false+.