Główczyn [ˈɡwuft͡ʂɨn] is a village in the administrative district of Gmina Mogielnica, within Grójec County, Masovian Voivodeship, in east-central Poland. It lies approximately 5 kilometres (3 mi) north of Mogielnica, 18 km (11 mi) south-west of Grójec, and 57 km (35 mi) south of Warsaw.