A two-stage model of peer influence was proposed. The model served as a framework for examining individual and relationship-specific differences in susceptibility to influence. The two stages are (1) the acquisition of a peer context and (2) conforming to the behavior of a peer. Data from a four-wave longitudinal study were used to assess (1) the initial selection of cigarette- and alcohol-using peers and (2) influence from peers. Relationship factors and variables identified as risk factors for substance use were hypothesized to increase susceptibility to peer influence. The results indicated that adolescents who did not value school achievement or spending time with parents were more apt than others to choose friends who smoked cigarettes more than they did. Adolescents who chose friends who drank more than they did not differ from other adolescents on any of the risk factors. Thus, low-risk adolescents were as likely to acquire a friend context where drinking was likely to occur as were adolescents who had more risk factors. When the second stage was examined, only high peer acceptance and high friendship quality resulted in adolescents being more apt to conform to their friend's substance-use behaviors.