You will get the "Object reference not set to an instance of an object." because the list2 exists inside another list (inside a template control and can not be accessed directly). If you want to filter this, you need to do a recursive FindControl (list1.FindControl("list2")) and then filter the control found. Another way to do this is to filter your datasource for list2. Have the pagereference as the parameter to the metod and make a codebehind method with a pagedatacollection with you add a filter on. ... .... For adding a filter to a pagedatacollection, see the FAQ in the support section on www.episerver.com or take a look at this: FilterSort sort = new FilterSort(FilterSortOrder.Alphabetical); sort.Filter(null, new FilterEventArgs(col)); /Øyvind