San Francisco Standard highlights Stuart study on community guardians
Two Urban Alchemy ambassadors on a streetcorner in San Francisco's Tenderloin.
A new study published today in PNAS Nexus led by Professor Forrest Stuart in collaboration with former Stanford PhD student Caylin Moore and Patrick Janulis of Northwestern University, offers evidence that unarmed community members trained in de-escalation and social services can reduce crime and disorder in high-need public spaces.
The research focused on Urban Alchemy, a San Francisco nonprofit that employs “ambassadors,” many of whom were formerly incarcerated. Their responsibilities include keeping streets clean, managing conflicts, connecting people with services, and discouraging public drug use.
Stuart, Moore, and Janulis analyzed reported crime over a five-year period at 624 San Francisco intersections. Using a statistical method that compared locations where ambassadors were deployed with similar intersections without ambassadors, the researchers found that overall crime declined by approximately 20 percent in areas where ambassadors were stationed. The largest reductions occurred in incidents related to behavioral health.
The findings suggest that trusted community members can serve as effective “capable guardians”—people whose presence and willingness to intervene can deter crime and disorder.
The study is featured in The San Francisco Standard.
Stuart, a MacArthur Fellow, directs the Stanford Ethnography Lab.
Moore graduated from Stanford Sociology's PhD program Spring 2026 and is now assistant professor of Sociology and Criminology at Pennsylvania State University.