The authors examined the contributions of the minority stress model, traditional masculine gender roles, and perceived social norms in accounting for gay men's use of alcohol, tobacco, illicit drugs, and risky sexual practices. Three hundred fifteen gay men recruited from listserv communities completed measures assessing internalized homophobia, stigma, antigay physical attack, masculinity, and perceptions of normative health behaviors, along with health risk behaviors of alcohol use, illicit drug use, smoking, and high-risk sexual behaviors. Pearson correlations supported several hypotheses; social norms and masculinity variables were significantly related to health risk behaviors. Four multiple regression analyses indicated that masculinity and perceptions of social norms predicted health risk behaviors. Additionally, a significant interaction was found between minority stress and perceptions of social norms. The clinical implications of the findings, limitations, and suggestions for future research are discussed. (Contains 1 table and 1 figure.)