Behavioral health challenges both contribute to and are exacerbated by homelessness. To better understand behavioral health and homelessness, we examined data from the California Statewide Study of People Experiencing Homelessness. Our latest report examines the relationship between homelessness, substance use, and mental health, providing critical insights for policymakers, program leaders, Continuum of Care leaders, and healthcare systems.

Key Findings

  • Nearly half (48%) of people experiencing homelessness in California have complex behavioral health needs—regular drug use, heavy drinking, hallucinations, or recent psychiatric hospitalization.
  • About one-third (35%) report regular drug use; 42% reported that they began to use regularly after the first time they experienced homelessness.
  • Methamphetamine (32%) is the most common drug used, followed by opioids (11%) and cocaine (3%).
  • More than one in four (28%) people with regular drug use or heavy alcohol use sought treatment during their current episode of homelessness but couldn’t access it.

We thank the California Health Care Foundation (CHCF) for supporting this work. 

Resources

Reports
Behavioral Health and Homelessness
March 19, 2025
Behavioral health challenges both contribute to and are exacerbated by homelessness. To better understand behavioral health and homelessness, we examined data from the California Statewide Study of Pe...
Event
Webinar: Behavioral Health & Homelessness: Findings from CASPEH

Homelessness and behavioral health issues (mental health and substance use) are intertwined. Join the UCSF Benioff Homelessness & Housing Initiative for a webinar to learn about this complex…

Virtual Event
Press Release
Press Release
New UCSF BHHI Report Examines the Relationship Between Homelessness and Drug Use
March 19, 2025
The University of California, San Francisco Benioff Homelessness and Housing Initiative (BHHI) today released a report that examines the issues of homelessness and behavioral health (substance use and...

“This new UCSF BHHI report makes clear that homelessness and behavioral health are inextricably linked — and that the solutions lie in expanding supportive housing, fully integrating health and housing systems, and investing in proven evidence-based approaches. Policymakers and communities across the country should take these findings seriously.”

Jeff Olivet
Senior Advisor, Initiative on Health and Homelessness at the Harvard T.H. Chan School of Public Health and former Executive Director, U.S. Interagency Council on Homelessness

“While housing is the solution that every person needs to end their homelessness, this report also underscores the critical importance of supportive services that meet people's complex needs. To address homelessness, communities must have available community-based and culturally appropriate service and treatment options that meet people where they are and help get them to a place where they will be able to thrive.”

National Alliance to End Homelessness

“CSH proudly endorses UCSF's report highlighting the deep connection between homelessness and behavioral health challenges. The report showed that individuals with these histories can flourish in affordable housing with supportive services. Without such support, homelessness can exacerbate behavioral health issues. CSH supports the report's recommendation to expand housing, services, and treatment options in order to build healthy communities where everyone can succeed.”

Deborah De Santis
President and CEO, Corporation for Supportive Housing (CSH)

“The data tells us that homelessness exacerbates behavioral health challenges and that over 80% of people with such challenges can thrive in permanent supportive housing. If we work across systems to prevent people from becoming homeless, bolster trauma-informed care and end practices that displace people, and increase access to housing, we can build healthier, safer communities for everyone. In our pursuit of racial and housing justice, we appreciate that this report names incorporating culturally-specific models for treatment involving community leaders as a recommendation for supporting people in achieving their recovery goals.”

Stephanie Chan
Chief Strategy Officer, Funders Together to End Homelessness

“This report confirms what all know to be true: behavioral health challenges increase your chances of becoming homeless and being homeless increases your chances of facing significant behavioral health challenges. This report also does the important work of offering key solutions to addressing our dual behavioral health and homelessness crises.”

Karen Larsen
CEO, Steinberg Institute

“We extend our deepest gratitude to UCSF and the Benioff Homelessness & Housing Initiative for commissioning this critical report on the intersection of behavioral health and homelessness. The comprehensive research and evidence-based recommendations provided offer invaluable insights into the challenges faced by individuals experiencing homelessness and the urgent need for integrated care solutions. By shedding light on the complex behavioral health needs of this vulnerable population, UCSF continues to play a vital role in informing policy and driving meaningful change. We commend their dedication to advancing research that leads to compassionate, effective, and lasting solutions.”

Meghan Marshall
Executive Officer of the California Interagency Council on Homelessness