The current study employed parallel process and discrete time hazard regressions to examine the interplay among exposure to R-rated movies, sensation seeking, and initiation of alcohol use in a national U.S. sample (N = 6255) of adolescents, ages 10-14, who were followed over four waves spanning 2 years. There was a short-term reciprocal relation between watching R-rated movies and sensation seeking, but over the 2-year observation period, exposure to R-rated movies was associated with increases in sensation seeking and not vice versa. Sensation seeking also moderated the effect of watching R-rated movies on initiation of alcohol consumption such that exposure was associated with greater increases in initiation of alcohol use among low sensation than among high sensation seeking adolescents. The study provides empirical evidence of an environmental media effect on sensation seeking, and important new information about the relations among sensation seeking, media exposure, and adolescent alcohol use.