This paper argues for the validity of treating ideology as an independent variable along with economic and political variables in theories ofsocial change. Complementary theories of economic, political, and ideological change should enrich grand theories of social change like those ofMax Weber. The logical/analytical structures of Wallerstein's theory ofthe world economic system and Collins' theory ofgeopolitical change are used to propose some elements ofa theory ofideological change. Finally, some applications ofthe theory are suggested as possible contributions to ongoing questions in studies of the radical Reformation