The classical approach to the study of the transformation of social movements (here called the Weber-Michels model) predicts that a movement organization will become more conservative and that its goals will be displaced in favor of organizational maintenance. Using organizational and incentive analysis, the classical approach is subsumed under a more general set of concepts which lead to predictions about growth and change. The movement organization responds to the ebb and flow of sentiment in the larger society, to its relations with other movement organizations and to success or failure. Leadership and schismogenetic tendencies affect the nature and vicissitudes of its goals, and the recruitment and commitment of members. Neither greater conservatism nor organizational maintenance are iron laws.