A substantial amount of research has suggested that adolescents' attitudes and behaviors are influenced by peers; however, little is known regarding adolescents' individual variability, or susceptibility, to peer influence. In this study, a performance-based index from an experimental paradigm was used to directly measure adolescents' susceptibility to peers. A total of 36 adolescent boys participated in a "chat room" experiment in which they ostensibly were exposed to deviant or risky social norms communicated either by high-peer-status (i.e., popular, well-liked) or low-peer-status (i.e., unpopular, disliked) grade mates who actually were electronic confederates. Changes in adolescents' responses before and after exposure to peer norms were used as a measure of peer influence susceptibility. These same adolescents completed a questionnaire assessment at the study outset and again 18 months later to assess their actual engagement in deviant behavior and their perceptions of their best friend's engagement in deviant behavior. Only among adolescents with high levels of susceptibility to high-status peers was a significant longitudinal association revealed between their best friend's baseline deviant behavior and adolescents' own deviant behavior 18 months later. Findings support the predictive validity of a performance-based susceptibility measure and suggest that adolescents' peer influence susceptibility may generalize across peer contexts. (Contains 2 tables.)