Across different countries and with regards to different historical atrocities, policymakers, and others often hope that learning about historical intergroup atrocities will mobilize us to act for better intergroup relations today. Because it is ultimately the engagement of citizens that makes the difference between obsolete historical facts and dynamic collective memory, it is important to understand citizens’ reactions to materials about historical atrocities. However, the evidence from different disciplines is mixed. While some studies highlight possible negative effects (e.g., increased defensiveness), others underline the positive effects (e.g., support for democratic values and actors). Existing studies differ in terms of their treatment, and to some extent also how they measured the outcomes. Our research aims to comprehensively understand if and when reading about historical atrocities has positive vs. negative effects, and if it has any effect at all on contemporary intergroup relations. We employ survey experiments in five different countries: Canada, France, Germany, Spain, and the US. These countries are very similar to each other in many aspects (e.g., Western, democratic, and economically developed), but differ with respect to memory culture and the specifics of the atrocities. The treatment is as uniform as possible. Participants read a text that provides information on what happened, when it happened, the scale of the atrocities, the suffering of victims, and the complicity of civilians. Our analysis points to positive effects on intergroup relations and highlights the importance of structural factors (e.g., memory culture and public discourse).