This paper defines the concepts of gender and social reproduction as developed in feminist theory and discusses their utility for synthesizing recent historical research on women. We review literature on the emergence, institutionalization, and reorganization of “separate spheres” in nineteenth and early twentieth century Europe and North America. Focusing on social class differences in family strategies, procreation, sexuality, consumerism, professionalization, and state policy, we argue that the organization of gender relations and social reproduction crucially shaped macrohistorical processes, as well as being shaped by them.