Utilizing the large, longitudinal Minnesota Twin Family Study (N = 2510; 96 % European American ancestry), we examined the influence of several person-environment transactions on adolescent substance abuse. We focused on the two childhood personality traits found to be most predictive of substance abuse in this sample-socialization (willingness to follow rules and endorse conventional values) and boldness (social engagement and assurance, stress resilience, thrill seeking)-and the environmental variables of antisocial and prosocial peers, academic engagement, parent-child relationship quality, and stressful life events. Path analysis revealed that low socialization had a selection effect for each environmental risk factor, that is, socialization at age 11 predicted environmental risk at age 14, after controlling for the stability of the environmental variables from ages 11 to 14. Antisocial peers and academic engagement at age 14 then mediated some of the risk of low socialization on substance abuse at age 17, but the majority of risk for substance abuse was accounted for by the stability of socialization from age 11 to 14. Boldness at age 11 also increased risk for substance abuse, but did so primarily via a direct effect. The findings help to parse the nature of person-environment transactions across multiple personality traits and contextual risk factors that contribute to adolescent substance abuse.