Transgender explodes the notion that male and female are discrete categories. Transgender people change sex or inhabit third (or multiple) sex, androgynous, or fluid identities. I theorize this by developing and then critiquing poststructuralist transgender theory. A poststructuralist theory of transgender disassociates sex and gender, models both as constructed, and emphasizes the technologisation and commodification of the body. Poststructuralist accounts can, however, entail denial of bodily limitations, erase transgender people's subjective experience, and overlook social and political factors, such as the importance of gender categories as a basis for identity politics. I argue for the deconstruction of gender binaries to be combined with the development of a gender-pluralist, flexible, model of gender. This points to the replacement of bipolar models of gender with a gender spectrum, with important implications for conceptualizing gender. My analysis is based on empirical research with a range of transgender people.