This study is the first to examine whether executive functioning (EF) abilities moderate longitudinal associations between peer victimization and engagement in physically and relationally aggressive behavior. Participants were 61 children (9–13 years, M = 10.68, SD = 1.28; 48% male) drawn from a partially clinical sample who were assessed at two time points, approximately 12 months apart. At time 1, children were administered a battery of EF tests; adult reports of children's relational and physical victimization and use of relational and physical aggression were collected. At time 2, adult‐reported aggression was re‐collected. Regression analyses tested whether EF ability moderated the association between peer victimization and increased engagement in aggression. Form‐specific (e.g., physical victimization predicting physical aggression) and cross‐form (e.g., physical victimization predicting relational aggression) models were tested. EF moderated the association between physical victimization and increases in physical aggression over time and between relational victimization and increases in relational aggression over time. Physical victimization predicted increases in physical aggression only among children with poor EF. However, relational victimization predicted increases in relational aggression for children with good EF skills but decreases in relational aggression for children with poor EF skills. Interaction effects for cross‐form models were not significant. Results suggest that there are distinct risk factors implicated in children's engagement in physical and relational aggression. Established cognitive vulnerability models for engagement in physical aggression should not be assumed to apply to engagement in relational aggression.