In Dutch secondary education, lessons on sexual diversity are a mandatory part of the curriculum since 2012. Do these lessons have an effect, especially among Orthodox-Christian pupils, who have an above-average negative stance towards gay people? In this article we primarily take a look at the second lesson of the teaching method ‘Homo in de Klas’ (“Gay in the class”, 2009), during which an encounter with a Christian gay person takes place. A total of 636 pupils from third grade havo/vwo participated in this quasi-experimental research, in which 37 classes filled out a questionnaire before and after the lessons and 35 pupils participated in interviews. The data of a multilevel linear regression show a decrease in stereotyping but no increase in empathy in the experimental group. Additionally, data from the interviews suggest a number of moderators, such as guest speaker’s appearance and authentic story. This is consistent with the knowledge that such encounters do have a greater effect when there is little familiarity, knowledge or room for discussion regarding sexual diversity in the pupils immediate surroundings.