How did the wrong-body discourse (WBD) become the dominant medicalised discourse in Canada and the United States? What ideological effects did this dominance have? To address these questions, I conducted a critical discourse analysis informed by Foucauldian genealogy. I analysed texts written in, or translated into, English for a medical-expert audience from the earliest mentions of wrong bodies in 1864 to the institutionalisation of the WBD in the DSM-III diagnosis of transsexualism in 1980. I argue that through the medicalisation of gender variance, the three tenets of the WBD—wrongness of the body; disjuncture between sex and gender; surgical and hormonal solution—developed individually and were brought together by medical experts into a coherent discourse in the mid-1960s. Two main factors likely contributed to the dominance of the WBD: the lack of dependence on any particular etiology that made the WBD compatible with a wide variety of explanations, and the very small number of medical experts responsible for the majority of publications on gender variance all using the WBD. I further argue that medical experts, faced with challenges to their treatment of gender-variant people, turned to the idea of true transsexualism to stabilise the newly-formed WBD and legitimate their treatment of gender variance. In addition to the three tenets of the WBD, true transsexualism also included characteristics and assumptions that medical experts expected gender-variant people to embody if they wanted access to treatment. Through these expectations, medical experts produced a set of norms against which all gender-variant people were judged as legitimate or not, namely, one of the first iterations of transnormativity. / Graduate