This exploratory case study examined how two teachers used a comparative approach to teach genocide histories in a Holocaust Literature elective course. Through interviews and observations, we studied how the teachers guided students in comparing genocides as well as how they used survivor testimonies in their instruction. We found that teachers engaged in three types of comparison throughout the unit under study: defining genocide as the basis of comparison, discussing similarities and differences, and expanding students' knowledge of genocide beyond the Holocaust. The teachers set up their classrooms as safe places for learning about genocide as difficult history, yet they did not shield their students from its horrors. Additionally, they encouraged their students to take action against genocide outside of the classroom. This study adds to the limited empirical research on teaching comparative genocide and has implications for curriculum design and teacher education.