There are few historical studies about the sex education of Australian youth. Drawing on a range of sources, including the oral histories of 40 women and men who attended two single-sex, selective high schools in a provincial Australian city (Newcastle, New South Wales) in the 1930s-1950s, this paper explores the adolescent experience of sex education and gender relations. First, it outlines attempts by the New South Wales State Government and the Newcastle community to introduce sex education, especially during the moral panic about sexuality generated during World War Two. Second, it charts the experiential realm of growing up for adolescent females and males. Hegemonic gender ideology meant that sexual knowledge was mostly kept secret from adolescent girls, and that frightening lies about sexual matters proliferated in the vacuum created by sexual ignorance. For adolescent males, sexual knowledge, while still shrouded in myth and mystery, was more readily available. Indeed sex education classes were introduced at the boys' school in the 1950s, while the girls' school remained silent on the matter for the entire time. At the theoretical level, the paper suggests that the dominant ideology of femininity included sexual ignorance and was allied to the ideology of childhood innocence. Both ideologies were artefacts of patriarchal power. (Contains 4 notes.)