March 20, 2025

This week, the University of California San Francisco Benioff Homelessness and Housing Initiative (UCSF-BHHI) released a new report, Behavioral Health and Homelessness. Based on findings from the 2023 California Statewide Study of People Experiencing Homelessness (CASPEH), the report examines behavioral health challenges within California’s unhoused populations and provides recommendations for policymakers and community stakeholders to improve supports for those experiencing homelessness and behavioral health issues.

The report acknowledges a bidirectional, yet complicated, relationship between behavioral health issues and homelessness. While mental health and substance use issues increase an individual’s risk of experiencing homelessness, the experience of homelessness undoubtedly exacerbates behavioral health conditions. To help explore the needs and experiences of people experiencing homelessness with behavioral health challenges, the report focuses on the experiences of those with the highest acuity, or “complex behavioral health needs.” Those with complex behavioral health needs are defined as having one or more of the following:

1. Regular illicit drug use (three times per week or more)
2. Heavy episodic alcohol use (six or more drinks in one sitting at least weekly)
3. Current hallucinations (within the past 30 days)
4. Psychiatric hospitalization within the last six months

Key findings from the report include:

• 48% of people experiencing homelessness report having complex behavioral health needs. 89% of people with complex behavioral health needs reported unsheltered homelessness, while 68% of people experiencing homelessness without complex behavioral health needs reported unsheltered homelessness.
• 35% of people experiencing homelessness report regular drug use. Among this group, 42% reported beginning regular drug use after their first experience with homelessness.
• Methamphetamine is the most commonly used illicit drug; 32% of adults experiencing homelessness reported regular methamphetamine use and 11% reported regular opioid use.
• 28% of those with regular drug use or current heavy alcohol use reported wanting substance use treatment but being unable to access it during their current experience with homelessness.

Regardless of behavioral health needs, affordability remains the most commonly reported barrier to accessing housing. However, those with complex behavioral health needs were more likely than those without to report additional barriers to housing, including lack of adequate housing and navigation support, missing documentations, criminal justice records, and credit issues. To improve housing outcomes for people experiencing homelessness with complex behavioral health needs, the report provides recommendations to embed additional supports and services through evidence-based practices, partnered with subsidized housing.

For additional information on the report and other studies published, please visit the UCSF BHHI website.