Jack Drescher, MD discusses the study of human sexual identities is changing, and these changes oblige analysts to think about sexualities in ways never envisioned by their psychoanalytic forbears. These changes also require that they be aware of some of the limitations imposed upon by their own theoretical traditions. Toward that end, this presentation begins with a definition of terms related to modern conceptions of sexuality and sexual identities. This is followed by a review of historical assumptions underlying the theory of bisexuality. The next section introduces the audience to the role of categories and hierarchies in general, and to the clinical meaning of sexual hierarchies in particular. This is followed by a discussion of the meanings and uses of the “natural.” The final section concludes with a commentary on intersexuality as an example of both the social and surgical construction of gender.