The present study examines whether one aspect of problematic adjustment--poor self-concept--contributes to victimization, is a consequence of victimization, or both. A sample of 187 third- through seventh-grade children were tested in both the fall and spring of the academic year on four self-report, self-concept measures: (a) global self-esteem, (b) social self-esteem, (c) self-efficacy for assertion, and (d) self-efficacy for aggression. At both times of testing, children also reported classmates who manifested both victimized and aggressive behaviors. Results indicated that social self-esteem and self-efficacy were both antecedents of victimization even after controlling for T1 levels of victimization. Social self-esteem was also an outcome of victimization after controlling for T1 levels of social self-esteem. A secondary consideration of the research was to investigate whether poor self-concept is predictive or an outcome of aggression, and results are discussed. Theoretical explanations for the specific relations found are advanced.