Background: This study examined adolescent delinquency and alcohol use in relation to young adult crime, alcohol use disorders (AUDs), and risky sex. Analyses further examined the influences of late childhood involvement in these problem behavior outcomes, with mediation through teen delinquency and alcohol use, and examined differences in the pathways for youth from low- compared to middle-income backgrounds. Method: Multiple-group latent growth curve modeling was conducted using data collected from a sample of 808 youth followed from age 10 to age 24. Self-report assessments included delinquent involvement, alcohol use, and sexual activity in late childhood; delinquency and alcohol use in adolescence; and crime, AUDs, and risky sex in early adulthood. Results: Late childhood delinquent involvement was associated with young adult crime, AUDs, and risky sex indirectly through adolescent delinquency, and had a persistent direct effect on crime. Adolescent delinquency also mediated the relation between early sex onset and crime. Early alcohol use predicted a higher level of, and a faster rate of increase in, adolescent drinking, which predicted, in turn, young adult AUDs and risky sex. Significant group differences indicated stronger associations between adolescent delinquency and each young adult outcome for youth from low- compared to those from middle-income backgrounds. Conclusions: Early intervention may help prevent the development of crime, AUDs, and risky sex behaviors, especially among disadvantaged youth. (Contains 3 tables and 1 figure.)