Emotion can result from interpreting group actions as reflecting on the self due to an association between the two. This volume considers the nature of collective guilt, the antecedent conditions necessary for it to be experienced, how it can be measured, as well as how collective guilt differs from other group based emotions. Research from Australia, Canada, Germany, Israel, the Netherlands, Northern Ireland, and the USA addresses critical questions concerning the who, when, and why of the experience of collective guilt. The political implications of collective guilt and forgiveness for the past are considered, and how those might depend on the national context. How collective guilt can be harnessed and used to create a more peaceful future for groups with a history of violence between then is emphasized.