I don't know much about O'Cartys. I have only read that they were a small clan in Ireland and that is about it. The McCartys came to PA as early as 1690 and my family dropped the "Mc" around 1850 as did some other branches in the area. I haven't quite figured out which McCarty's we came from yet though. They say that McCarty comes from McCarthy which is interesting because there was no "H" in the Irish alphabet until long after the name was in use. In most cases I believe that it is silent and signifies a different pronunciation. Most of the McCarthy's were from Munster, Ireland. Did I meet you once at Toys R Us in P'burg? I remember them paging me and a woman saying that was her name too.