Using data from the Add Health, this study examined multilevel factors of adolescent smoking after controlling for the baseline smoking behavior and individual characteristics. Results showed that peer, family and school were all important life domains contextually influencing subsequent smoking behavior among adolescents. Time spent with peers, best friend smoking and household member smoking were associated with higher risk. Parent-child closeness, parental control, attending a private school and having a higher percentage of Hispanic students at school were protective factors. Significant interaction effects were found between parental control and household member smoking and between parent-child closeness and communication. None of the neighborhood- and state-level factors were significant in the final full model but they were significant in reduced models. More proximate social contexts appear to play a more direct and immediate role in adolescent smoking than macro-level factors. An ecological model incorporating multiple social systems seems more fruitful than single-system models to reveal etiology of adolescent smoking. (Contains 4 tables.)