Resource mobilization theory became the dominant paradigm for studying social movements in the 1970s because it was better able to account for the 1960s cycle of protest than previous theories of collective behavior. After almost two decades of theoretical development, the resource mobilization framework is now under increasing challenge. Drawing on research on women's movements in the United States, this article identifies ten issues which collectively pose a major theoretical challenge to the dominance of resource mobilization theory and which may initiate a paradigm shift to a new framework for the study of social movements.