Data was gathered in a nationwide survey of 17,592 students at 140 colleges and universities. A student’s particular collegiate environment accounted for only a small portion of the overall variation in perceptions of campus drinking norms. Within each campus context perceptions varied widely. More permissive perceptions of the norm were significantly associated with greater personal alcohol abuse even after controlling for personal attitudes, thus suggesting that perceiving a permissive environment encourages students to drink more heavily than they would otherwise based on their personal attitudes. The detrimental impact of perceiving more permissive drinking norms was greatest for students whose own attitudes about drinking were already permissive. Alcohol abuse prevention efforts on college and university campuses may be more effective in reducing problem drinking by including a proactive strategy that addresses perceived norms in campus initiatives. Mass media campaigns, orientation programs and curricular initiatives can be designed to inform entire campus populations of the true norms based on accurate survey research. The power of peer influence can be positively engaged to constrain drinking problems as students internalize less exaggerated perceptions of peers. Tables, references