The association between increases in antipathy involvement over time and growth in aggression and victimization was investigated. Results indicated that antipathy involvement was dynamically related to aggression and victimization, controlling for peer rejection. However, these longitudinal associations depended on the gender of the child. In particular, increases in the number of antipathy partners over time were associated with time-dependent increases in physical aggression and physical victimization for boys only. In contrast, growth in antipathy involvement predicted increases in relational aggression for girls only. These results suggest that negative peer relations at the dyadic level are important dynamic predictors of change in aggression and victimization over time. Implications for the practice of school psychology are discussed. (Contains 6 tables.)