Risk factors for the onset of cigarette smoking were examined by means of a prospective longitudinal study in 1230 Norwegian adolescents aged 12-18. In particular the importance of role modelling was focused. The findings revealed that the age period between 12 and 15 is most important when it comes to the initiation of smoking. Among those who initiate smoking, the incidence rates of quitting is low, indicating that most of the initiators quickly seem to develop a relatively stable smoking habit. Smoking initiation can be divided into two stages. The first, experimental one, is predicted by peer modelling and low socioeconomic status (SES). The second, establishing a regular pattern of use, is predicted by modelling of parental smoking and the interaction between female sex and low SES. Studying the characteristics of the regular smokers cross-sectionally, peer modeling showed the strongest correlates. Studying the predictors of the transitions longitudinally, the more complex picture described above was uncovered. This indicates that the complexity of the role modelling process can only be simulated adequately by means of prospective research methods and by paying attention to such parameters as gender, age, SES and stage in the smoking acquisition process.