Through a sociological reconstruction of Judith Butler's performative theory of gender and an empirical study of the transsexual community, Patrícia Soley-Beltran dispels misunderstandings about the Butlerian notion of the body and its problematization of the sex/gender distinction, while illustrating recent transformations in feminism, from gay and lesbian identity politics to queer theory and transgender movements. The interpretive framework, constituted by the performative theory of social institutions (mainly developed by science sociologists Barry Barnes and David Bloor) and the notion of artificial type (developed by philosopher Martin Kusch), shares affinities with Butler's thought: problematizing the nature/culture dichotomy and highlighting the social construction of scientific knowledge about the body. The comparative empirical study approaches the British and Spanish transsexual communities as informants of the processes of adaptation to gender norms by all members of society. The analysis of their testimonies not only provides data about hegemonic popular knowledge on gender and the influence of medical categories in its definition, but also clarifies without prejudice or partisanship the characteristics of this community and situates it within its ideological and socio-political contexts, thus illuminating the cultural landscape in which legal and medical actions take place.