To examine the effects of normative influences on adolescent smoking in Greece, a country with weak social norms against smoking and relatively ineffective tobacco control policies. A cross-sectional survey methodology was employed, and a representative sample of Greek high school students was recruited (N = 1,920, M age = 14 years). Normative beliefs, attitudes, perceived behavioral control, self-esteem, and intentions to smoke. Multiple-regression and mediation analyses were conducted. The effects of public smoking on intentions to smoke were mediated by beliefs of perceived prevalence of smoking among peers, subjective norms, and situational temptations. Self-esteem significantly moderated the effects of subjective norms on intentions to smoke. Prosmoking norms in one's environment become internalized into biased normative beliefs about smoking, and increase susceptibility to smoke under social pressure. The effect of subjective norms on intentions to smoke was stronger among adolescents with low self-esteem, suggesting that self-esteem may act as a vulnerability factor in the process of smoking initiation. PsycINFO Database Record (c) 2009 APA, all rights reserved.