The study found that beyond the significant impact of childhood maltreatment, peer-group control predicted risky alcohol use and delinquent behavior. Peer-group control and the motivation to be popular with one's peer group exacerbated the negative effects of parental physical maltreatment on delinquent behavior. Boys' experiences of peer group control were more strongly linked to alcohol use and delinquent behavior than the peer-group experiences of girls. The findings suggest that efforts to mitigate the effects of childhood maltreatment should include a focus on the nature of and motivation for peer-group associations during adolescence. Schools and communities should develop youth-related activities that promote positive development and guided interaction that sets norms for the values and objectives of peer interaction. A total of 1,558 (804 girls) high school students from 3 schools in Southwestern Ontario (Canada) participated in this study. A participant's experiences of maltreatment were assessed with the Childhood Trauma Questionnaire. The assessment of peer-group processes involved several measures of group control, leadership/hierarchy, and peer pressure to behave in antisocial ways. Twelve items measured adolescents' motivation for peer popularity and associated control behavior. Measures of the frequency of alcohol use and binge drinking were taken from the National Longitudinal Study of Children and Youth. Fifteen items measured general delinquency, including weapon use, theft, school suspension, selling drugs, and physical violence. 3 tables, 5 figures, 50 references, and appended peer-group control items