http://msmvps.com/blogs/luisabreu/archive/2009/04/09/the-mvc-framework-the-acceptajaxattribute.aspxThere might be some scenarios where you have methods that should only be invoked for AJAX requests. In those cases, you can use the AcceptAjaxAttribute to decorate those methods. This is an ActionMethodSelectorAttribute which overrides the IsValidForRequestenCommunityServer 2008.5 SP2 (Build: 40407.4157)