In a longitudinal design, this study examined psychosocial mediators of the effects of parental educational attainment on adolescent smoking acquisition and also examined whether smoking transition had different antecedents among adolescents from families of varying educational backgrounds. Parents' low educational attainment acted as a moderate to strong risk factor for the initial onset of smoking among middle school girls. Some of this effect was mediated by the higher smoking prevalence among both parents and friends of these adolescent girls, as well as by their lowered expectations for academic success. However, these variables only partially mediated the effect of parent education. There were few indications of differential antecedents of smoking acquisition among adolescents from less and more highly educated families. Implications for public health antismoking campaigns are discussed.