<p>Permanent supportive housing (PSH) is a community-based housing model for people experiencing homelessness that provides stable housing with a range of voluntary supportive services, such as case management, healthcare, mental health, and substance use treatment services. Understanding (1) the impact of PSH on health outcomes and (2) factors that predict retention in PSH are essential for implementing support systems to address the needs of PSH residents. To address this need, 259 residents living in Santa Clara County, California were followed for two years to evaluate: (1) predictors of retention in PSH compared to transitioning to other stable non-PSH housing or returning to homelessness; (2) the longitudinal impact of PSH on mental, physical, and social health outcomes among residents remaining in PSH; and (3) moderators of these effects. Results indicate, first, that older age, being male, and lower mental health and PTSD symptoms increased the likelihood of remaining in PSH compared to moving to non-PSH stable housing. Lower mental health symptoms also predicted greater likelihood of PSH retention compared to returning to homelessness. Second, among residents who remained in PSH for 2 years, results indicated significant improvements in quality of life, health satisfaction, mental health symptoms, PTSD symptoms, substance use, and social isolation. Third, the effects of PSH on health outcomes were not significantly moderated by demographics. Study findings demonstrate the promise of PSH, in keeping people housed and significantly improving residents’ health outcomes, but strategies are needed to improve mental health and substance use service delivery in PSH.</p>