It is well-known that male delinquency increases dramatically at approximately the same time as the onset of puberty. Evidence regarding whether individual variation in pubertal development is associated with delinquency, however, is mixed. In recent research, for example, Williams and Dunlop (1999) found that boys who matured either early or late engaged in more delinquency than boys whose development was on time with their peers. The current study hypothesized that the combination of pubertal development (PD) and other risk factors increases the likelihood of delinquency. The researchers expected that characteristics of the relationship with parents, association with delinquent peers, academic performance, race, parents' education, and living on public assistance would have stronger effects on delinquency than PD. Using data from the first two waves (1995-96) of Add Health, information was obtained on development, delinquency, aggression, sexuality, substance use, family background, and friends' behaviors. There were four separate measures of self-reported delinquency: violent crime, property crime, drug use, and precocious sexuality. The violence index consisted of the summed score of six different violent events. The study found strong positive relationships between PD and violence, on one hand, and property crimes, drug use, and precocious sexual behavior on the other; however, there was no evidence that these effects were due to the impact of puberty on risk-taking, maladjustment, dominance behavior, or autonomous behavior. There was evidence that PD interacted with social factors; possibly mature boys are more strongly influenced by delinquent friends. PD also had stronger effects on the delinquency of boys who were academically successful and thus generally at lower risk to engage in delinquency. 5 tables, 2 figures, and 41 references