The purpose of this study was to assess the relative contribution of friends' and parents' smoking on the age of smoking initiation. A sample of 812 preadolescents, who were part of an accelerated longitudinal design, participated in the study over a 4-year period. Three smoking trajectory groups were first established: an age 11-12 starters group (5.7% of the sample), an age 12-13 starters group (11.1% of the sample), and an age 13-14 starters group (7.9% of the sample). A fourth trajectory group included the children who had not started smoking by age 15 years and who represented the majority of the participants (75.4%). After controlling for parental education, gender, and participants' behavioral and academic maladjustment, a series of logistic regressions revealed that parents' smoking assessed during the same year predicted membership in the age 11-12 starters trajectory group. Both parents' and friends' smoking predicted membership in the age 12-13 starters group. Finally, only friends' smoking predicted membership in the age 13-14 starters group. The results are discussed in light of the controversy about the contribution of parents' and friends' smoking behavior to smoking initiation in adolescents.