The paper situates the new field of men's studies in the context of the evolution of women's studies. It argues that men's studies' distinctive feminist approach to men is a necessary complement to women's studies, citing paradigmatic examples of new perspectives. In tracing women's studies' development, the paper argues that reconceptualizations of "gender" resolve tensions between much of women's studies' non-essentialist empirical social science describing "sex roles" and much of feminist theory's essentialist celebrations of women's core selves.