The purpose of this study was to examine two aspects of context for peer aggression: national individualism and distributions of socioeconomic status in the school. School administrators for each school reported on their perceptions of the frequency of bullying and violence in their school. The sample comprised 990 school principals/headmasters from nationally representative samples of schools in 15 countries surveyed as part of the larger IEA Civic Education Study (Torney-Purta, Lehmann, Oswald, & Schulz, 2001). A national context of individualism was associated with violence but not bullying. Schools with high socioeconomic diversity had more bullying than homogeneously low or high socioeconomic status schools. In addition, diverse schools had more violence than affluent schools. Results suggest that bullying and violence should be investigated as separate constructs. Furthermore, contexts, such as national culture and school socioeconomic diversity, are important in understanding the prevalence of bullying and violence in schools internationally. (Contains 3 tables and 2 figures.)