Objective: To evaluate the effect of a campus-wide social norms marketing intervention on alcohol-use perceptions, consumption, and blackouts at a large, urban, public university. Participants: 4,172 college students (1,208 freshmen, 1,159 sophomores, 953 juniors, and 852 seniors) who completed surveys in Spring 2015 for the Spit for Science Study, a longitudinal study of students' substance use and emotional health. Methods: Participants were e-mailed an online survey that queried campaign readership, perception of peer alcohol use, alcohol consumption, frequency of consumption, and frequency of blackouts. Associations between variables were evaluated using path analysis. Results: We found that campaign readership was associated with more accurate perceptions of peer alcohol use, which, in turn, was associated with self-reported lower number of drinks per sitting and experiencing fewer blackouts. Conclusions: This evaluation supports the use of social norms marketing as a population-level intervention to correct alcohol-use misperceptions and reduce blackouts.