Quality of peer relationships and perceived peer antisocial behavior were examined as moderators of the link between negative parenting and externalizing behavior problems in school from middle childhood to early adolescence. Data on negative parenting (i.e., unilateral parental decision making, low supervision and awareness, and harsh discipline) were collected from 362 parents in the summer preceding the adolescents' entry into Grade 6. Adolescent reports of positive peer relationships and peer antisocial behavior were assessed in the winter of Grade 7. The outcome measure was teacher report of adolescent externalizing behavior in the spring of Grade 7, controlling for externalizing behavior in Grade 5. High levels of friendship quality and peer group affiliation attenuated the association between unilateral parental decision making and adolescent externalizing behavior in school; this was particularly true when adolescents associated with peers perceived to be low in antisocial behavior. In addition, having low-quality peer relationships and having peers perceived to be highly antisocial further amplified the association between unilateral parental decision making and adolescent externalizing behavior problems. Finally, high levels of friend and peer group antisocial behavior exacerbated the predictiveness of harsh discipline for adolescents' externalizing behavior.