Project Summary Using mobile technology that most students already have in their pockets, we propose a novel use of SMS text messages to change campus drinking norms. We aim to correct exaggerated perceptions of drinking norms, and thereby reduce excessive drinking, by delivering push notifications representing accurate, campus-specific, pro-moderation descriptive norms (what others do) and injunctive norms (what others approve of). We predict that with repeated exposure over time, this information will compete with other sources of normative information to which students are exposed during their first year of college. In this exploratory R21, we will develop and refine message content and pilot test the delivery methods. First, with input from student advisors, we will survey a representative sample of 300 students about personal behaviors and attitudes, and perceived descriptive and injunctive norms, for a wide range of alcohol-related behaviors and protective strategies. Extending the range of behaviors previously studied in the norms literature, these data will yield campus-specific norms and identify items with the largest self-other discrepancies as potential sources of corrective feedback. Second, we will translate the content into a pool of text messages and solicit feedback, iteratively, from approximately 40 first-year students. Third, we will conduct a pilot test of the SMS-delivered pro-moderation norms intervention to evaluate the effect of receiving these text messages on perceived peer norms, and high volume drinking and consequences. First year students (N=120) who are underage but report risky drinking (>4/day or >14/week for men; >3/day or >7/week for women) will be randomly assigned to two conditions differing by text content: alcohol norms or control. All will receive 5-6 text messages per week over 12 weeks. Process measures, 3-month post-test, and 3-month follow-up assessments will yield feasibility, acceptability, and preliminary outcome data to inform future larger scale randomized trials. We predict that the experimental condition will be acceptable and interesting, will protect against increases in pro-drinking perceived norms, and will result in less risky drinking and fewer alcohol consequences, relative to control. This project has public health significance because high volume drinking has harmful consequences to self and others, and has proven to be hard to change on college campuses; individual-level interventions typically have limited reach, and environmental policy changes can be hard to implement. This mHealth intervention offers a novel approach to prevention during a period of transition, and this study will provide proof-of-concept that SMS text messages can be used over time to correct exaggerated alcohol norms, a mechanism known to reduce excessive drinking and its negative consequences.