Early adolescents vary in their susceptibility to peer influence on delinquency. However, it is still less clear which factors explain this variation and how these factors relate to each other. In this study, 10 factors that may moderate peer influence were investigated. A sample of 868 participants was followed across six occasions from seventh to ninth grade. Multilevel longitudinal models showed that descriptive norms among the classmates, based on aggregated self-reported delinquency, predicted individual delinquent behavior across time. When each factor was considered separately, the effect of classmates’ delinquency was stronger for males and adolescents scoring higher on impulsivity, risk tolerance, social dominance, cool appearance, unstructured spare time activities, and lower parental supervision. No moderation effects were found for age, self-worth, and social acceptance. In a model containing all significant moderators, only male gender remained significant, indicating boys’ higher susceptibility. Implications for theory and preventing negative peer influence are discussed.