Ontario is the only North American, English-speaking jurisdiction to include philosophy in secondary schools. In this first study to examine Ontario high school philosophy courses, we investigated what sorts of textbooks teachers used, how they used them, and the reasons for their pedagogical choices when using textbooks. Despite claims that philosophy promotes critical thinking, an online survey of 53 high school philosophy teachers and personal interviews with a subset of 14 revealed their use of textbooks did not match this ideal. Teachers cited insecurities with knowledge, a lack of pedagogical training, their own perception that students were incapable of challenging texts, and pressure to meet provincial curriculum policy demands as factors that contributed to their pedagogical choices.