The question of justice is as old as humanity itself, and history provides us with endless examples of interpersonal and intergroup conflicts in which lives were lost and resources allocated in order to do “what is right.” From a psychological perspective, it is impossible to determine what “right” means in any objective and independent fashion. Thus, a political and social psychological framework is needed to address two critical justice-related questions: Why do people care about justice? And why do people sometimes accept the suffering of others while at other times reacting strongly to injustice? These are the fundamental questions that research on the justice motive attempts to answer, a concept defined as the extent to which people are motivated to promote fairness. This entry reviews ...