http://msmvps.com/blogs/matthieu/archive/2009/06/16/subobjectset.aspxWith EF, when you use TPH or TPC inheritance mapping scenarii, the EntitySet is on the base class. As I mentioned often in the past with EF v1, you can add a property in your context which returns the EntitySet.OfType<MySubType>(). Ok it’senCommunityServer 2008.5 SP2 (Build: 40407.4157)