The author studied peer crowds on a college commuter campus and examined the relation between self-reported alcohol use and perceived peer crowd norms for alcohol use. College students (N = 271) completed questionnaires to determine their peer crowd affiliation and frequency and amount of alcohol use. The author assessed perceived peer-crowd affiliation norms with a series of vignettes describing the typical student that would be associated with each peer crowd. Analyses revealed identifiable peer crowds among college students that represent different patterns of alcohol use both in self-reported alcohol use among students in a peer crowd and in the perceived norms for alcohol use in each peer crowd. The author described the relation between self-reported use and the perceived use by members of one's peer crowd.