Preparing students to be effective citizens is a longstanding goal of public education. Historical content provides illustrative opportunities for civic learning. Teaching about the Holocaust exemplifies this approach. Employing an experimental research design with 865 secondary school students, we analyze effects on civic outcomes from learning about the Holocaust through a school-sponsored trip to a Holocaust museum. We find that lessons about the Holocaust increase students' support for civil liberties and deepen historical content knowledge, but decrease religious tolerance. High school students and those from college-educated households drive increases in support for civil liberties, and these students are more likely to donate to human rights causes as a result of the intervention. Middle school students and those from less-educated households drive the negative religious tolerance effect. These findings suggest that history lessons can produce meaningful impacts on civic educational outcomes. However, a stronger educational foundation that comes with engaging with challenging political issues may be a vital prerequisite to avoid undesirable consequences.