OBJECTIVES: This study investigates factors related to the positive mental health of older Australian gay men, who are challenged by both age- and sexuality-related stigma. METHODS: A national online survey was conducted among 422 gay-identified men aged 40 years and older. Positive mental health was measured using the Short Warwick-Edinburgh Mental Well-being Scale (SWEMWBS). RESULTS: Regression analyses revealed men were psychologically healthier if they were employed full-time, had a higher income, were in a relationship, received greater social support, had many close friends, felt connected to the gay community, believed the public felt positively toward their group, and had not experienced discrimination in the past year. A multivariate linear regression found social support to be the most important of all these factors, with support from friends particularly critical. DISCUSSION: These findings provide new guidance to health agencies that seek to improve the mental health and well-being of older gay men.