Originally published in Bristow, J. and Wilson, A.R. (eds) (1993) Activating Theory: Lesbian, Gay, Bisexual Politics, London: Lawrence and Wishart. Reproduced by permission of the author. This article offers what has become a classic formulation of bisexual epistemology. Eadie points to the many ways in which bisexuals and bisexuality have been excluded from lesbian and gay discourses and communities in the UK and USA, and argues that this is not merely accidental, but is rather a ‘symptom’ of a much deeper epistemological issue. He suggests that homosexuality as such is predicated on its distinction from heterosexuality, and vice versa; and that, in turn, that distinction is predicated on the elision of bisexuality. To acknowledge bisexuality, according to Eadie, is to acknowledge that the distinction between heterosexuality and homosexuality is inherently unstable, and he argues that this instability should be welcomed, not just because the recognition of bisexuality and bisexuals is a desirable goal in itself, but because the breakdown of the heterosexual/homosexual dyad will ultimately transform the ways in which sexuality is lived and organised. Drawing on lesbian and gay studies, feminist theory, anthropology, and film and literary criticism, Eadie suggests that bisexuality offers a ‘hybrid’ position from which to rethink sexual diversity.