Multiple levels of influence should be considered in interventions aimed at the adolescent smoker, including psychological, addiction, peer and parental influences. However, the mechanism by which these variables influence the process of smoking cessation in adolescents is not well elucidated. Therefore, this prospective study tested two models among 850 adolescent smokers, specifying the direct and indirect relations between adolescents' readiness to quit smoking, levels of nicotine dependence, and smoking behavior of their parents and friends. One year later smoking cessation was assessed. Results showed that, among adolescent smokers, readiness to quit was positively associated with quit attempts, while nicotine dependence was inversely associated with successful cessation. Instead of a direct relation, parental and peers' smoking were inversely related to smoking cessation through nicotine dependence. The findings emphasize that interventions should be developed and tested within and outside the school setting, as well as within the family situation. In addition, the strong impact of nicotine dependence on successful cessation indicates that a more direct approach is needed to lower nicotine dependence among adolescents. (c) 2008 Elsevier Ireland Ltd. All rights reserved.