A great deal of research has focused on delineating the nature and extent of sex differences in cognitive abilities and performance. However, recent research and theory suggest that cognition maybe much more socially situated than psychology has recognized. Distinguishing ''sex'' from ''gender'' places sex difference research in a context that conceives of culturally-produced gender as the operation of a complex system of social classification and hierarchy. The gender system is conceptualized as operating at three levels: Sociocultural, interactional, and individual. By using this framework, we move the focus of study from individual or group differences in cognition to documenting how different levels of the gender system interact to create, maintain, and interpret sex differences.