Compared to adolescents with low exposure to smoking in movies, those with high exposure are about three times as likely to try smoking or become smokers. We have observed this effect in nationally representative samples using cross-sectional and longitudinal designs. This effect remains statistically significant after controlling for numerous other traditional risk factors, such as personality, parenting style, and sociodemographics. Indeed, the movie-smoking exposure effect on adolescent smoking initiation is greatest among those traditionally considered at lower risk for smoking, such as those low in sensation seeking and those whose parents do not smoke. In this article, we consider possible moderators and mediators of this important media effect as well as health-policy implications. The take-home message is that eliminating smoking in movies may prevent a substantial number of adolescents from smoking.