The review arrives at a politically charged moment. The authors explicitly note that rapid policy shifts in several jurisdictions have favored treatment-focused approaches to addressing homelessness, often framing addiction treatment as a gateway to housing. Against that backdrop, the team set out to determine what the published evidence actually says about the key components and outcomes of housing-based support models. Their answer, drawn from more than 13,000 screened records, is nuanced but firm: the strongest and most consistent evidence favors low-barrier Housing First models, while evidence for treatment-first models remains more limited and heterogeneous.

Methodologically, the review was designed for speed without sacrificing rigor. The researchers searched five major databases — CINAHL, Embase, Medline, APA PsycInfo, and Web of Science — for peer-reviewed studies published between January 1, 2000 and April 30, 2025. After screening 13,393 records, they included 57 studies: eight randomized controlled trials, thirty quasi-experimental studies, six qualitative studies, five mixed-methods studies, and eight other designs. Study quality was appraised using Joanna Briggs Institute tools, and the team extracted data on intervention characteristics, model features, comparison conditions, and outcomes spanning housing stability, substance use, mental health, and service utilization. That breadth of study designs, from gold-standard randomized trials to real-world quasi-experiments, strengthens the ecological validity of the findings while also revealing where the evidence base thins out.

From this body of work, four distinct program types emerged. Scattered-site models place participants in independent apartments dispersed across a community, with support services delivered where people live. Single-site models concentrate housing and on-site services within one building, offering concentrated support but sometimes recreating institutional environments. Transitional housing provides time-limited accommodation intended as a bridge toward permanent housing. Finally, outreach support-to-housing programs begin with street-level engagement and gradually connect individuals to housing. Each architecture carries different assumptions about what people experiencing homelessness need first — and each produces different patterns of outcomes in the literature.

On the headline question of housing stability, the verdict was unambiguous. Housing First models consistently improved housing stability compared with treatment-first, linear treatment-contingent models, or treatment-as-usual conditions. This finding held across randomized trials and observational studies alike, reinforcing what has become a robust international evidence pattern: when the immediate goal is ending homelessness, removing preconditions works. The mechanism is conceptually straightforward. Requiring people to demonstrate sobriety or complete treatment before accessing housing creates a barrier that many with active substance use disorders cannot clear, leaving them cycling through shelters, hospitals, and the street. Housing First inverts that sequence, treating stable housing as the platform from which health improvements become possible.

The picture grows more complicated when the review turns to substance use outcomes. Effects of Housing First on substance use were heterogeneous across studies, with alcohol-related outcomes improving more consistently than illicit drug use. Some trials found meaningful reductions in alcohol consumption and alcohol-related harms among participants in scattered-site Housing First, while effects on illicit drug use varied widely, with some studies showing no significant differences compared with control conditions. This heterogeneity matters for policy. It suggests that housing alone, while transformative for stability, does not automatically resolve the full spectrum of substance use health needs — particularly for stimulant and opioid use, where the evidence for spontaneous improvement in the absence of integrated treatment is weakest.

Mental health outcomes followed a similarly mixed pattern. Some studies reported no differences between Housing First and comparison conditions on measures of psychiatric symptoms, while others documented improvements in psychological distress. The reviewers caution against reading these mixed results as evidence of failure. Mental health trajectories among this population are shaped by many factors beyond housing, including trauma history, physical health, social connection, and access to psychiatric care. What the data do support is that Housing First does not worsen mental health outcomes — a persistent concern among critics — and in several studies actively reduces distress, all while delivering far superior housing outcomes.

Beyond housing and behavioral health, the review examined acute healthcare utilization and costs. Evidence for reductions in psychiatric hospitalization and overall costs was described as promising but less definitive than the housing stability findings. Several studies suggested that Housing First participants spend fewer days in hospitals and emergency departments, generating offsets that partially or fully compensate for the cost of housing and support services. However, the reviewers found this evidence less consistent across studies, likely reflecting differences in health system contexts, measurement approaches, and follow-up durations. For policymakers weighing fiscal arguments, the review suggests the cost case is plausible but not yet ironclad — an area where longer-term, more rigorous economic evaluations are needed.

The authors’ conclusions translate directly into policy recommendations. They call for scaling up low-barrier Housing First programs while integrating expanded voluntary substance use treatment, mental health care, harm reduction services, and wraparound supports within housing. The emphasis on voluntariness is significant: the evidence does not support coercive treatment mandates as a condition of housing, but it does support making comprehensive, choice-based services readily available to tenants who want them. The four program types identified in the review offer a menu rather than a single prescription — scattered-site models may suit people seeking independence, while single-site and transitional models may serve others — but the common thread is that housing comes first, not last.

The review also candidly maps the gaps that remain. While some treatment-first models reported positive outcomes, the evidence base for them was more limited and heterogeneous than for Housing First, making head-to-head comparisons difficult. The authors highlight the need for further comparative research and, critically, more robust longer-term studies to identify which specific program components best support substance use health among this high-needs population. As jurisdictions worldwide grapple with visible homelessness crises and intensifying debates over housing versus treatment paradigms, this review offers a rare commodity: a rigorously synthesized evidence base. Its message is neither that housing solves everything nor that treatment is irrelevant, but that the sequence matters — and the science says house people first, then wrap every effective service around them.

Subject of Research: Housing-based support models for adults experiencing homelessness with substance use and mental health needs

Article Title: Housing-based support models for individuals experiencing homelessness, substance use and mental health needs: a rapid review

Article References: Somefun, O. D., Kerman, N., Corace, K., Taha, S., Buckley, L., & Stergiopoulos, V. (2026). Housing-based support models for individuals experiencing homelessness, substance use and mental health needs: a rapid review. Addiction Science & Clinical Practice. https://doi.org/10.1186/s13722-026-00716-9

Image Credits: AI Generated

DOI: 10.1186/s13722-026-00716-9

Keywords: homelessness, Housing First, substance use, mental health, harm reduction, treatment-first models, housing stability, rapid review, addiction science, psychiatric hospitalization, supportive housing, public health policy