Social influences on adolescent substance use.

Objective: To assess the overtime relationships between adolescent and peer substance use and parenting practices.

Methods: Five times from sixth to ninth grade, students (n=2453) in 7 middle schools reported smoking, drinking, and marijuana use; the number of substance-using friends; and parent practices. Relationships were assessed using latent growth curve modeling.

Results: Adolescent substance use predicted the growth in substance-using friends, and substance-using friends predicted adolescent use, except for smoking. The negative over-time relationship between parenting practices and adolescent substance use was mediated by the growth in the number of substance-using friends.

Conclusions: The results are consistent with both selection and socialization effects and provide evidence of the protective effects of positive parenting practices.