Historical analysis of sex education materials, as well as of the debates that surround them, can shed light upon the construction of sexuality in particular contexts. This article examines some of these materials and debates as a window into the construction of "homosexuality" and "the homosexual" in mid-twentieth century New Zealand. It is argued that "the homosexual" as a category was not clearly demarcated during this period, and that "heterosexuality" "per se" did not appear in debates over "sex instruction" until the 1950s. Earlier notions of self-control were reasserted during the post-war moral panic over young people's sexuality, and homosexuality was sometimes regarded as a symptom of social rebellion and thus a universal potential as much as a characteristic of a fixed sexual minority. Contemporary psychology and responses to the war blurred the boundaries between "homosexuality" and "normal" sexuality, ensuring the ongoing instability of what has more recently been termed the "homo/hetero binary". (Contains 20 notes.)