The current study tested a model examining both the direct and mediated effects of Ethnic Cultural Norms (ECN) on cigarette use in a sample of Mexican American youth (ages 11-14; N=921). Contextual risk factors (peer smoking and family smoking) were included as potential moderators of this mediational relationship. A product of coefficient (alpha beta) method to test the significance of the mediated effect [Evaluation Review 17 (1993) 144.] was adapted to assess the mediation of interaction effects. Results suggested that Tobacco Avoidance Self-Efficacy mediated the protective influence of ECN on cigarette use. However, as peer smoking increased, the influence of ECN on cigarette use diminished, though it remained a significant, protective influence on cigarette use. Results are discussed in terms of the potential synergy between ECN and social influence training in tobacco preventive intervention development among youth of Latin descent.