From the time they stepped ashore at Plymouth and Salem, the New England Puritans have commanded attention, partly because of the boldness of their undertaking, partly because of its material success, but also because of the tension, excitement, and hope aroused by a large-scale effort to deal rationally with society. Their attempt to direct human relations into a consistent pattern derived from Biblical precepts has been the focus of my own interest in the Puritans. In previous works I have discussed their concepts of family relationships and of civil government. Currently I am engaged in a study of the way their ideas affected economic problems. In the ensuing pages I have tried to examine the origins and history of an idea that they considered more important for society than domestic, political, or economic ones, the idea of membership in the church.