Background: Male students' achievements in female-dominated study programs have garnered limited research attention. This study investigates the relationship between psychology students' perceived diversity climate and their learning outcomes in a gender-mixed computer-supported collaborative learning (CSCL) course in introductory psychology. Our main hypotheses were that the diversity climate-learning outcome relationships would be stronger for male (gender minority) than for female students (gender majority). Methods: This study used data from a large sample of university first-year students at a blended learning university (n = 1,172, 75% female) with three points of measurement in a 9-week CSCL assignment. Findings: Moderated-mediation regression analyses confirmed that students' perceptions of the diversity climate in their CSCL group were significantly related to gains in online learning self-efficacy among male, but not female students. Furthermore, by increasing gains in self-efficacy, climate perceptions also translated into better quiz performance among male students. Contributions: This study shows that for men perceived diversity climate is a significant determinant of their individual learning outcomes. This calls for paying more attention to the minority perspectives of males in female-dominated psychological programs to better understand why this is the case.