Background: HIV viral suppression is associated with health benefits for people living with HIV and a decreased risk of HIV transmission to others. The objective was to identify demographic, psychosocial, provider and neighborhood factors associated with sustained viral suppression among gay, bisexual, and other men who have sex with men. Methods: Data from adult men who have sex with men (MSM) enrolled in the Miami-Dade County Ryan White Program (RWP) before 2017 were used. Sustained viral suppression was defined as having an HIV viral load < 200 copies/ml in all viral load tests in 2017. Three-level (individual, medical case management site, and neighborhood) cross-classified mixed-effect models were used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CI) for sustained viral suppression. Results: Of 3386 MSM, 90.8% were racial/ethnic minorities, and 84.4% achieved sustained viral suppression. The odds of achieving sustained viral suppression was lower for 18-24 and 25-34 year-old MSM compared with 35-49 year-old MSM, and for non-Latino Black MSM compared with White MSM. Those not enrolled in the Affordable Care Act, and those with current AIDS symptoms and a history of AIDS had lower odds of achieving sustained viral suppression. Psychosocial factors significantly associated with lower odds of sustained viral suppression included drug/alcohol use, mental health symptoms, homelessness, and transportation to appointment needs. Individuals with an HIV physician who serves a larger volume of RWP clients had greater odds of sustained viral suppression. Neighborhood factors were not associated with sustained viral suppression.(Continued on next page)