College students, particularly those who drink heavily, tend to overestimate the prevalence of heavy drinking among their peers. A self-regulation model predicts that feedback of undesirable deviation from normative standards would result in correction of behavior toward perceived norms. From a screening of 568 college students, sixty-four heavy drinkers were identified and offered the opportunity to participate in a survey study of drinking. Of these, twenty-six accepted and returned questionnaires with detailed information regarding their drinking practices. These were randomized to receive or not receive, by return mail, personal feedback of their drinking relative to population norms. At an independent follow-up interview, feedback subjects showed greater reduction in weekly consumption and typical intoxication levels, relative to controls. This simple feedback intervention, requiring no personal contact, may be a cost-effective strategy for reducing risky drinking.