Prior studies of the relationship between smoking by parents and their children have considered only current smoking by parents. In this study of 12- to 14-year-old adolescents, however, lifetime parental smoking was more strongly correlated with adolescent smoking than was current parental smoking. Indeed, lifetime parental smoking was as strongly correlated as peer smoking with adolescent smoking, and peer smoking is often considered to be the main determinant of adolescent smoking. These findings suggest that the relative role of parent smoking in adolescent smoking has been underestimated, and that new explanations for the association between parental and adolescent smoking are necessary.