Background-People encounter large amounts of sometimes-inconsistent information about risks and benefits of alcohol consumption, and about what constitutes "low-risk" or "moderate" drinking.Methods-We used 150 in-depth interviews linked to questionnaire data to learn how people define moderate drinking and to describe the relationships between definitions, attitudes, and beliefs about moderate drinking and individuals' drinking patterns.Results-People adhere to definitions of moderate alcohol consumption that could put them, or others, at risk for short-or long-term negative consequences of drinking. Definitions that confused increased tolerance of alcohol with moderate drinking, and those that defined moderate drinking by the absence of short-term negative consequences or ability to maintain control over drinking, ignore long-term risks of heavy consumption. Individuals with risky attitudes were also more likely to report at-risk drinking practices.Conclusions-Americans have complex beliefs about benefits and risks of alcohol consumption, and public health officials have not succeeded in conveying strong or clear messages about what constitutes low-risk drinking or about dose-response effects. Different (but more consistent) approaches to public education may be needed to increase knowledge about drinking-related risks. The prevalence of diverse norm-based definitions suggests that alternative normative information could help people reassess their own consumption.