Peer smoking is a strong correlate of smoking behavior, predicting initiation, regular smoking and dependent smoking [1]. Evidence suggests that peer influence in established friendship networks and selection of peers in establishing new friendships both play roles in the observed similarity among peers for a number of risk behaviors [2–4] including smoking [5–6]. A variety of theories have been used to postulate and understand mechanisms by which peer smoking behaviors increase the risk of smoking onset and maintenance of smoking including Social Learning, Primary Socialization, Social Identity and Social Network Theories [7–8]. The key elements of these theories and empirical evidence suggest that, affiliation with smoking peers provides direct opportunities to initiate smoking and models for learning how to smoke (peer influence). Smoking peers also provide a socially reinforcing context of friends’ encouragement and approval [9–10] that maintains smoking behavior and a smoker social identity (peer influence and selection). Consistent with the reinforcement/maintenance effects of affiliating with smoking peers, peer smoking is associated with multiple stages of smoking and its influence extends beyond adolescence into adulthood [1].
