This meta-analysis summarizes 113 research reports worldwide (121 cross-sectional and 7 longitudinal studies) on age differences in ethnic, racial, or national prejudice among children and adolescents. Overall, results indicated a peak in prejudice in middle childhood (5–7 years) followed by a slight decrease until late childhood (8–10 years). In addition to differences for the various operationalizations of prejudice, detailed findings revealed different age-related changes in prejudice toward higher versus lower status out-groups and positive effects of contact opportunities with the out-group on prejudice development. Results confirm that prejudice changes systematically with age during childhood but that no developmental trend is found in adolescence, indicating the stronger influence of the social context on prejudice with increasing age.