This article presents Moral Exclusion Theory as a way to systematize the study of complex issues in peace education and to challenge the thinking that supports oppressive social structures. The authors define its 2 key concepts: moral exclusion, the limited applicability of justice underlying destructive conflicts and difficult social problems; and moral inclusion, the emphasis on fairness, resource sharing, and concern for the well-being of all underlying peace building. They demonstrate the relevance of Moral Exclusion Theory in 4 key areas of peace education: (a) education for coexistence, (b) education for human rights, (c) education for gender equality, and (d) education for environmentalism. They then describe 2 common issues faced by schools, bullying and textbook bias, to demonstrate that moral exclusion is common and how students and staff can redress it. The article concludes with the challenge to use peace education as a tool for moral inclusion and for bringing about a world in which justice applies to all.