Project Summary/Abstract College student heavy drinking is related to a wide range of negative consequences16,26-28. The social influence of close peers (i.e., one’s social network) is a well-documented predictor of college student drinking17. One form of socialization occurs through social media. Higher rates of exposure to alcohol-related content on social media is linked to higher alcohol consumption and negative alcohol-related consequences in college student samples20,21. Specifically, among college students, exposure to alcohol-related pictures and/or text shared by online peers was strongly associated with increases in consumption up to 6 months later22. However, these studies did not identify close peers within their social network (which could consist of both online and in-person peers) or report the frequency of different modalities of alcohol-related social media content posted. Recent research highlights the need to understand the influence of close peer relationships, both in-person (assessed via traditional social network research) and online via social media. No studies have examined how this intersection (i.e., the qualities of in-person social network members sharing risky content on social media) or how the type of content shared affects problematic drinking among college students. Moreover, college student social networks vary over time rapidly, even changing substantially within an academic year36-38,84; thus, social influences on individual drinking behavior may be changing. This has yet to be studied within the social media content exposure context. The proposed study would be the first longitudinal examination of how changes in alcohol-related social media content students are exposed to (via changes in egocentric social networks) are associated with changes in viewer alcohol outcomes. The specific aims examine: 1) how changes in exposure to alcohol-related social media content (via changes in the composition of college students’ social networks) are associated with college drinking over time, 2) the effects of modality of alcohol-related content (photo, video) shared by the social network, and 3) qualities (i.e., emotional closeness, drinking buddy status) of social network members sharing alcohol-related content. The present research is in line with NIAAA’s initiatives to improve our understanding of behavioral factors which are associated with problematic drinking among college students (both underage and of legal age). Overall, this award will assist the applicant in establishing themselves as an independent researcher in a tenure-track faculty position with a program of research focused on how social influences via peers and social media are linked to college student drinking behaviors. Long- term goals involve applying for future awards that seek to increase student drinker awareness and develop interventions to buffer the effects of exposure to alcohol-related social media content shared by close friends on alcohol o...