Should homelessness interventions target housing or mental health treatment?

The number of unhoused individuals in the U.S. reached a record high of 770,000 at the end of 2024 (Porter 2024). Homelessness policy remains a source of vehement partisan debate. Some argue that homelessness is, in fact, a housing problem, with permanent housing solutions required to help those most in need. Others argue that those who are chronically unhoused must have issues that go beyond lack of affordable housing; instead, untreated mental illness and substance use are often at the heart of the problem. Should homelessness policy target housing or mental health treatment? My research reveals surprising insights about which approach actually saves more lives—findings that have important implications as the Trump administration prepares to dramatically shift federal homelessness policy.

In the 1990s, homelessness advocates developed the concept of “Housing First” – the idea that for those most in need, highly subsidized permanent housing should be given unconditionally, before any other underlying issues are addressed. Advocates argue that requiring conditions for housing only creates barriers to care, and that it is hard to address underlying mental health issues without having a stable home first.

Housing First programs are pitted against "Treatment First" approaches – which require people to address mental health and addiction before finding permanent, unsubsidized housing on their own. In these models, individuals generally enter transitional housing, or temporary communal housing in which substance use and mental health treatment are required, sometimes along with sobriety. After a one to two-year stay in these transitional homes, individuals are deemed ready to enter regular, generally unsubsidized housing. Proponents of Treatment First argue that Housing First does not address the root cause of homelessness nor incentivize any behavioral changes.

How does prior research weigh in on this debate? Randomized controlled trials have consistently demonstrated that Housing First increases housing stability compared to those not enrolled in the program (see Kertesz et al. 2009). But what should these programs accomplish? Should homelessness programs primarily focus on housing stability, or are larger goals of improved health and general well-being even more important? Notably, Housing First’s effects on other outcomes, notably mental and physical health, remain unclear (NASEM 2018). Another problem with existing research is that  Housing First studies compare permanent housing to "no housing subsidy" – but this second group includes people in treatment programs as well as people getting no help at all.

My doctoral research at UC Berkeley aims to shed light on the long-term health benefits of Housing First versus Treatment First-style interventions, particularly for veterans, who have historically been overrepresented among the unhoused. Since the 1990s, the VA, along with the Department of Housing and Urban Development (HUD), have run a joint Housing First program. Known as HUD-VASH (VA Supportive Housing), the program offers housing vouchers to chronically homeless Veterans in the same style as Section 8. Concurrently, the VA has a large transitional housing program – called the Grant and Per Diem (GPD) program – which contracts out to third-party agencies, such as the Salvation Army, to run short-term, Treatment First-style housing, where Veterans can stay for up to two years. 

With highly granular data from the Department of Veterans Affairs, I study nearly 300,000 unhoused Veterans with mental illness, the primary group targeted for these programs. Beginning with their initial intake assessment, I follow these Veterans for three years, tracking program participation and long-term health outcomes. My research finds that Housing First significantly reduces long-term mortality, while Treatment First has minimal long-term health effects.

Why do Housing First methods appear to be so much more successful at improving health than Treatment First-style interventions? Doesn’t Treatment First explicitly target health? Well, one answer could be housing alone: as echoed by prior research, I find that Housing First has a large impact on housing stability, suggesting that mental health treatment is not required for individuals to succeed in maintaining housing. Meanwhile, Treatment First increases long-term housing stability by a much smaller margin. Those who initially enter transitional housing may be unsuccessful in finding a permanent home after the program ends, leaving individuals on the street and vulnerable.

What about addressing mental health and substance use? Following the philosophy of Treatment First, my research shows that transitional housing increases engagement with mental health care, but only while individuals actively live in transitional housing units. So, perhaps these short-term interventions do not lead to long-term behavioral changes.

Another hypothesis – often posited by Housing First advocates – is that once individuals have a stable home, they’ll voluntarily seek out the mental health treatment they need. I’m actually not finding evidence of this phenomenon: Housing First seems to have no effect on mental health care utilization. My results suggest that stable housing saves lives, and that required mental health treatment doesn't make up for a lack of permanent housing.

These findings are critically important as policymakers decide how to allocate homelessness funding. The Trump administration has already indicated it will move away from Housing First initiatives, with major funding cuts to HUD, in favor of treatment-first style interventions (Hart 2025). Former U.S. Interagency Council on Homelessness director Robert Marbut, appointed by Trump in his first term, began the shift away from Housing First, stating that he believed in “housing fourth” – i.e., linear style programs that emphasize mental health and addiction treatment (Eide 2020). Marbut has since emphasized that “The Trump administration is laser-focused on ending Housing First” (Hart 2025). Despite the administration’s promise to curb street homelessness, my work suggests that scaling back Housing First initiatives will likely have the opposite effect.

References
Eide, Stephen. 2020. “Housing First and Homelessness: The Rhetoric and the Reality.” Manhattan Institute.
Hart, Angela. 2025. “Trump turns homelessness response away from housing, toward forced treatment.” CBS News.
Kertesz, Stefan G, Kimberly Crouch, Jesse B Milby, Robert E Cusimano, and Joseph E Schumacher. 2009. “Housing First for Homeless Persons with Active Addiction: Are We Overreaching?” Milbank Q, 87(2): 495–534. 
National Academies of Sciences, Engineering, Health and Medicine Division, Board on Population Health and Public Health Practice, Policy and Global Affairs, Science and Technology for Sustainability Program, and Committee on an Evaluation of Permanent Supportive Housing Programs for Homeless Individuals. 2018. “Evidence of Effect of Permanent Supportive Housing on Health.” In Permanent Supportive Housing: Evaluating the Evidence for Improving Health Outcomes Among People Experiencing Chronic Homelessness. National Academies Press (US). 
Porter, Justin. 2024. “The Evening: Record Homelessness in the U.S.” The New York Times.