The purpose of this meta-analysis was to use theory and research on diversity, attitudes, and training to examine potential differential effects on affective-based, cognitive-based, and skill-based outcomes, to examine potential moderators of those effects with a focus on affective-based outcomes, and finally, to provide quantitative estimates of these posited relationships. Results from 65 studies (N = 8465) revealed sizable effects on affective-based, cognitive-based, and skill-based outcomes as well as interesting boundary conditions for these effects on affective-based outcomes. This study provides practical value to human resources managers and trainers wishing to implement diversity training within organizations as well as interesting theoretical advances for researchers. Practitioners have quantitative evidence that diversity training changes affective-based, cognitive-based, and skill-based trainee outcomes. This study also supports and addresses future research needs. Copyright © 2012 John Wiley & Sons, Ltd.