The present study examined the role that descriptive norms play on the constructs of behavioral willingness, drinker prototype favorability, attitudes toward alcohol use, and perceived vulnerability for alcohol-related consequences, within the Prototype Willingness model. The primary objectives were to determine whether manipulated descriptive norms have an impact on these risk cognitions and whether this impact is stronger among adolescents with greater tendencies to engage in social comparison. Descriptive norms were manipulated by having 200 adolescents view older peers drinking or abstaining from alcohol via profiles from the social networking site, Facebook. The results indicate that viewing alcohol use among older peers is associated with greater willingness to use, more positive attitudes toward use, and lower perceived vulnerability. These results were not moderated by individual differences in the tendency to socially compare. Mediation analyses indicated that attitudes, perceived vulnerability, and perceptions of alcohol use among high school students mediate the relationship between viewing peer users and willingness to use. These results indicate that adolescents who perceive that alcohol use is normative in slightly older peers, as evidenced by Facebook profiles, are at higher risk for cognitions that have been shown to predict alcohol use, compared to adolescents who do not see alcohol use portrayed as frequently on Facebook.