Figure 3 presents the associations between peer substance use and adolescent alcohol use in the intervention vs. control conditions across high, medium, and low levels of OXTR risk. Two important inferences can be drawn from the figure. First, across each level of OXTR and intervention level, higher substance-using peer scores were related to higher alcohol use, demonstrating the consistency of this main effect. Second, the three-way interaction among OXTR, Intervention Status, and Peer Substance Use appears to be largely due to differences in alcohol use between intervention and control youth at high OXTR risk among adolescents who associate with low substance-using friends (see the far left end of the far right panel). Among these high OXTR risk, the effect of peer substance use on adolescents’ alcohol use diverge, taking on a relatively steeper slope in the control condition than in the intervention condition. The divergence can be accounted for by lower alcohol use among adolescents who affiliate with low substance-using friends within the control condition compared to the intervention. Thus, it seems that for a subset of youth—those with high
