School climate surveys have documented since 1990 the prevalence of homophobic violence and its negative impacts on its victims. However, little remains known on the way schooling can reproduce normative prescriptions relative to heterosexuality and conformity to gender expectations. This article analyses high school teachers’ practices regarding sexual diversity and suggests that teachers can come to play an important role in the propagation or the contestation of these norms. Considering the complicity of schools in the perpetuation of gender and sexual orientation norms appears to be a necessary criterion for the full inclusive education for LGBTI students.