Using data from a diverse statewide sample of 10th-grade adolescents in California, in 1996-97, this study investigated the associations between peer influence variables and susceptibility to smoking. Peer influence variables included attitudes about the social consequences of smoking and subjective norms, as described by the Theory of Reasoned Action. Among never-smokers (N=2681) and ever-smokers (N=4248), attitudes about social consequences of smoking and subjective norms each were associated with an increased risk of susceptibility to smoking. The model explained a larger proportion of the variance in susceptibility among ever-smokers than among never-smokers. Results indicate that peer influences, including perceptions of the social consequences of smoking and perceived social norms, may make adolescents susceptible to smoking.