that the association between substance use among close friends and the adolescents’ own substance use was moderated by their peer group status (Hussong, 2002), although our own data did not reveal three-way interactive effects1. The absence of a main effect for close friend substance use on the later stages heavy episodic drinking trajectories during young adulthood (i.e., slope 2) may reflect the attenuated influence that high school peers have on the later young adult years in terms of heavy episodic drinking. However, it is possible that substance use among current (i.e., adult) peers also play an influential role on drinking behaviors during the later young adult years (Mrug and Windle, 2014); these data were not available for the current study, unfortunately. It is noted that an important limitation was that peer influences were modeled as unidirectional effects, in which close friends were assumed to predict adolescent heavy episodic drinking and not conversely. Adolescents at high genetic risk for alcohol use problems are perhaps even more influential to the peers around them, as early substance use is often associated with greater popularity and social influence (Brechwald and Prinstein, 2011). Future studies of adolescent peer influences should feature more rigorous investigations of
