Aggressive behavior has been identified as both a cause and consequence of peer victimization, but relatively little is known about what might explain this association. The first goal of this study is to examine two social cognitive biases, rejection sensitivity and disrespect sensitivity, which may account for the relationship between victimization and aggression. While there is some support for the longitudinal relationship between victimization and aggression, others have failed to identify such relationships. Moreover, the concurrent relationship between victimization and aggression varies in magnitude. The second goal is to explore two physiological processes underlying emotion processes, RSA and EDA, in response to peer rejection, as moderators of the relationship between victimization and aggression. Participants were 67 (58% male) adolescents between the ages of 12-15 and one parent. Self-reports of victimization and reactive and proactive aggression and parent-reports of aggression were collected. Physiological data were collected during a task designed to simulate peer rejection. Results indicated that victimization was indirectly related to reactive aggression via angry rejection sensitivity and disrespect sensitivity and victimization was indirectly related to parent-reported aggression via angry and anxious rejection sensitivity. RSA moderated the relationship between victimization and reactive aggression and EDA reactivity moderated the relationship between victimization and proactive aggression and parent-reported aggression. The results support the theoretical relationship between victimization, aggression, and social cognition and highlight the role of physiological processes in adolescent adjustment.