Relative deprivation (RD) is the judgment that one is worse off compared to some standard accompanied by feelings of anger and resentment. Social scientists use RD to predict a wide range of significant outcome variables: collective action, individual achievement and deviance, intergroup attitudes, and physical and mental health. But the results are often weak and inconsistent. The authors draw on a theoretical and meta-analytic review (210 studies composing 293 independent samples, 421 tests, and 186,073 respondents) to present a model that integrates group and individual RD. RD measures that (a) include justice-related affect, (b) match the outcome level of analysis, and (c) use higher quality measures yield significantly stronger relationships. Future research should focus on appropriate RD measurement, angry resentment, and the inclusion of theoretically relevant situational appraisals. Such methodological improvements would revitalize RD as a useful social psychological predictor of a wide range of important individual and social processes.