In response to the international turmoil, violence, and increasing ideological polarization, social psychological interest in the topics of legitimacy and social justice has blossomed considerably. Social psychologists have explored the psychological underpinnings of people’s reactions to injustice and illegitimacy, including the behavioral and psychological consequences of the motivation to view individual outcomes and governmental systems as just and legitimate. Although injustice and illegitimacy are clearly related at conceptual and theoretical levels, these two rich literatures are rarely integrated. Social justice researchers have focused on how people make sense of particular instances of injustice, whereas legitimacy researchers have tended to focus primarily on people’s reactions to unfair systems of intergroup relations. This 11th volume of the Ontario Symposium series brings together the work of leading researchers in fields of social justice and legitimacy to facilitate the cross-pollination and integration of these fields. The contributions address broad theoretical issues and cutting-edge empirical advances, while illustrating the diversity and richness of research in the two fields. By uniting these two domains, this volume will stimulate new directions in theory and research that seek to explain how and why people make sense of injustice at all levels of analysis.