Contemporary efforts to treat sex offenders are rooted in the post-Second World War era, in which an unshakable faith in science convinced many Canadian parents that pedophilia could be cured. Strangers in Our Midst explores the popularization of the notion of sexual deviancy as a way of understanding sexual behaviour, the emergence in Canada of legislation directed at sex offenders, and the evolution of treatment programs in Ontario. Popular discourses regarding sexual deviancy, legislative action against sex criminals, and the implementation of treatment programs for sex offenders have been widely attributed to a reactionary, conservative moral panic over changing sex and gender roles after the Second World War. Elise Chenier challenges this assumption, arguing that, in Canada, advocates of sex-offender treatment were actually liberal progressives. Drawing on previously unexamined sources, including medical reports, government commissions, prison files, and interviews with key figures, Strangers in Our Midst offers an original critical analysis of the rise of sexological thinking in Canada, and shows how what was conceived as a humane alternative to traditional punishment could be put into practice in inhumane ways.