Two dll's to register for GAC

My guess is you need to register both if one depends on the other so it can find the other one. (I suspect, if they are relatively local, though, you don't need to, but the best way to find out is to give it a try!) You should always strong name dlls that go into the GAC using sn.exe and use the gacutil.exe to place them in the GAC. Hope this helps! -Mike