Abstract
Externalizing problem behavior is a robust predictor of early adolescent substance use (SU); however, findings regarding internalizing problems have been mixed, suggesting that there may be important moderators of the relationship between internalizing problems and SU. The present study used a community sample (mean age was 12.1 at the first assessment, 55% women, 83% White) to test a longitudinal latent variable interaction structural equation model to examine whether externalizing problems moderated the relationship between internalizing problems and SU. Peer delinquency was tested as a mediator in the model and prior levels of the mediator and outcome were controlled at each wave to establish temporal precedence. Results suggested that (1) internalizing problems were protective against associating with deviant peers, but only at high levels of externalizing symptomatology, (2) higher levels of peer delinquency were associated with increases in SU, and (3) peer delinquency mediated the effect of the problem behavior interaction on SU. Our findings suggest that the impact of internalizing problems on peer delinquency and SU needs to be considered in the context of externalizing problems. Moreover, developmental models involving internalizing symptoms should consider that internalizing symptoms are generally protective against substance use in early adolescence.