Social commentary about prevention messages may affect their likelihood of acceptance. To investigate this possibility, student participants (N = 663) viewed 3 antimarijuana advertisements, each followed immediately by videotaped discussions involving 4 adults or 4 adolescents using either extreme or moderate language in their positive commentaries. The commentaries were expected to affect participants’ perceptions of the extent to which the ads were designed to control their behavior (perceived control), which was hypothesized to inhibit persuasion. Two indirect effects analyses were conducted. Marijuana attitudes and usage intentions were the outcome variables. Both analyses revealed statistically significant source by language interactions on participants’ perceived control (both p < .02). Further analyses revealed significant indirect effects of language extremity on attitudes and intentions through perceived control with adult, but not peer sources (both p < .05). These perceptions were associated with more negative marijuana attitudes and diminished usage intentions when adults used moderate (vs. extreme) language in their favorable ad commentaries (both p < .05). The findings may facilitate development of more effective prevention methods that emphasize the importance of the role of perceived control in persuasion, and the impact of interpersonal communication variations on acceptance of media-transmitted prevention messages.