Social-cognitive models have often been used in research on prevention in adolescent populations, even though the models were designed to describe adult behavior. The aim of the study reported here was to examine critically and constructively the five social-cognitive factors in the 'attitude, social influence, self-efficacy' (ASE) model. Methods. The examination draws on the results of a qualitative follow-up study of smoking initiation based on semi-structured interviews and observations of 12 adolescents in two Danish school classes, grades 7 and 8. The qualitative study was conducted in connection with and sampled from a large quantitative study and the results of both studies are discussed. In the analyses, we explored the ASE constructs according to how they are described in the ASE theory. Furthermore, we examined contradictions and aspects which are not explained in the model and if relevant discussed these aspects using other theoretical frameworks. Results. The results showed that aspects other than those in the ASE model are also important. Smoking initiation was often situational and unplanned and was sometimes used in negotiating social relationships and identity. Furthermore, the social-cognitive models are based on the assumption that adolescents talk about smoking norms and have a high degree of individual reflexivity, which is not always characteristic of adolescent behavior. Conclusion. Applying theoretical models in health research should be a continuous process of both applying the model and discussing the theoretical assumptions of the model when applied to a specific sample. The results of the qualitative study provide some support for use of the ASE model, but the results also suggest that further studies are needed to explore how social-cognitive models can be expanded to be more comprehensive behavioral models.