“Epidemic” models of transitions between stages of cigarette smoking describe the spread of smoking behavior through face-to-face encounters. An epidemic model was successfully fitted that allowed epidemic parameters to be conditioned on the smoking status of adolescents' parents. Model comparisons supported the conclusion that the transition from nonsmoker to trier involved social contacts, whereas the transition from trier to regular smoker was best modeled as a constant rate (i.e., did not depend on the population prevalence of smokers). The transition rate from nonsmoker to trier was more rapid in children of smoking parents than in children of nonsmoking parents. Adolescents with and without smoking parents did not differ in the rate of transition from trier to regular smoking.