In two separate university samples, the effects of individual drinking habits on perceived riskiness and estimated prevalence of drinking practices were studied. In both populations, self-reported drinking behavior was inversely related to perceived riskiness of heavy drinking and drunk driving, but inconsistently related to prevalence estimates for these behaviors. Abstainers also overestimated the commonness of heavy drinking and drunk driving much more than did drinkers who similarly did not engage in these behaviors. These findings are interpreted as consistent with self-serving motivational biases in information processing. Relative to men, women in both populations provided higher estimates of prevalence and riskiness.