Unity in Diversity was a randomized controlled trial of a culturally tailored HIV prevention intervention for African American men who have sex with men. The intervention condition was six group-based sessions and one individual session. The control condition was a single-session HIV prevention review. Participants were aged 18 years or older, identified as African American/Black race, reported having at least two sex partners in the prior 90 days (at least one of whom must be a male partner), unprotected anal sex with male partner in the prior 90 days, and willing to test for HIV. Retention exceeded 95% at 3-month follow-up. Results of multivariate logistic regression analysis adjusting for baseline risk, HIV status, and health insurance indicate intervention efficacy in decreasing the number of male sex partners and marginal effects on condom use with male partners and HIV-negative/unknown partners. Specifically, intervention condition was associated with increased odds of zero male sex partners (adjusted odds ratio [AOR] = 3.03, 95% confidence interval [CI] = 1.26-7.28), condom use with male partners (AOR = 2.64, 95% CI = 0.95-7.36), and HIV-negative/unknown status partners (AOR = 3.19, 95% CI = 0.98-10.38) at follow-up. These results contribute to the limited number of culturally appropriate models of HIV prevention intervention that are urgently needed for African American men who have sex with men to address their persistently high rates of HIV. (Contains 4 tables and 1 figure.)