The authors examined the effectiveness of motivational interviewing (MI) on club drug use and risky sex in non-treatment-seeking men who have sex with men (MSM). MSM (N = 150) were assessed and randomly assigned to 4 sessions of MI or an educational control intervention. Follow-up occurred at quarterly intervals for 1 year. Primary outcomes were days of any club drug use and number of unsafe sex acts. On average, club drug use declined during follow-up. A significant interaction effect showed that MI was associated with less club drug use during follow-up compared with education but only among participants with lower severity of drug dependence (p less than 0.02; small to medium effect size). MI did not result in a significant reduction in risky sex relative to education. The results support the use of MI targeting club drug use in at-risk or mildly dependent users not seeking treatment but not in more severely dependent users. MI does not appear effective in reducing risky sexual behavior in this population. (Contains 1 footnote, 2 tables and 2 figures.)