Although peer behavior and parent-child-conflict have been associated with adolescent and young adults’ behavior, prior studies have not adequately controlled for selection effects and other confounders, or examined whether associations change across the transition to adulthood or by race. Using annual data from young men followed from 17–26, within-individual change models examined whether substance use or offending increased in the year after boys began affiliating with friends who engaged in substance use/offending and/or experienced increased parent-son-conflict. Moderation analyses tested whether associations varied by age or race. Alcohol use, marijuana use, and offending (Black participants only) increased in the year after boys began affiliating with more peers who engaged in similar behaviors. Associations were strongest during adolescence for substance use. Parent-son conflict was not associated with the outcomes. Findings underscore the importance of developmental and racialized differences in understanding the role of social influences on young men's substance use and offending.

Extracurricular activities (ECAs) have been found to promote positive youth development and protect against misconduct and minor delinquency. However, little research has examined whether ECA participation predicts delinquency among at‐risk young men or considered how delinquent behavior, in turn, impacts ECA participation. This study examined extracurricular participation over three years in a sample of 1,216 justice‐involved young men (Mage = 15.29). Approximately half of the sample participated in ECA each year. A cross‐lagged panel model was used to examine the bidirectional association between ECA participation and two types of delinquency, school misconduct and criminal offending. The results suggest that ECA participation did not consistently predict subsequent delinquency. Rather, justice‐involved young men who engaged in more delinquency were less likely to participate in ECAs.