I’m using ASP.NET MVC 3. I was used to rely on filterContext.RouteData.Values to get parameters from the url var idEdited = filterContext.RouteData.Val... This works fine as long as the url does not have specific parameters, like here: http://www.mysite.com/myapp... However, when the parameter is not a routevalue anymore, like in the example below, then you would get a OfficeId= null when using the previous method : http://www.mysite.com/myapp... ......