Objective. This study examined the impact of future friends and the contribution of different social influence and selection processes in predicting adolescents' smoking behaviour by extending the theory of planned behaviour (TPB). We investigated the impact of previous smoking, direct pressure from friends, descriptive norms of present and future friends, smoking-based selection of future friends, and distinguished between reciprocal and desired friends. Design. A longitudinal design with three measurements was used. Methods. The sample consisted of 1,475 Dutch high school students (mean age = 12.7 years) that participated as a control group in the European Smoking prevention Framework Approach study at three measurements. Results. Structural equation modelling revealed that adolescent smoking was influenced by intention, previous smoking, descriptive norms of parents and siblings, and that desired as well as reciprocal friends were selected based on similar smoking behaviour. Future friends indirectly influenced adolescent smoking through intention, as did attitude, subjective norms of parents and siblings, previous smoking, and descriptive norms of reciprocal friends and siblings. Conclusions. The present results suggest that descriptive norms and selection of friends need to be considered as major factors explaining smoking behaviour among adolescents besides the TPB components. These insights contribute to the further refinement of smoking prevention strategies.