Overly positive self-perceptions have been generally associated with psychological health. Recent research has suggested, however, that these overly positive perceptions may also be associated with aggressive or violent behavior. The current study examined the relation between aggressive behavior and self-perceptions in an adolescent population (grades 7-12). We examined both cross-sectional and longitudinal relations, and looked at both change in individual differences and individual differences in change. We examined all longitudinal hypotheses bi-directionally. We used multi-dimensional measures of self-concept that are tailored specifically to assess domains relevant to adolescents.