The Urban Institute, along with our partners at The Evaluation Center at the University of Colorado Denver, evaluated the efficacy of supportive housing over a five-year period. The evaluation implemented a randomized controlled trial of 724 individuals. People eligible for the supportive housing program were randomly assigned to one of two groups; individuals in the treatment group were offered supportive housing services, while individuals in the control group received usual care services in the community. A total of 363 people were randomized into treatment, while 361 were placed in the control group. Of those in the treatment group, 79 percent (285 people) were located, engaged, and housed. We found the following:

• Denver SIB supportive housing program participants spent significantly more time in housing than those in the control group, as measured by housing assistance. Those referred to SIB supportive housing received 560 more days of housing assistance over three years, compared with those who received services as usual in the community.
• After accessing supportive housing, most participants stayed housed over the long term. Excluding those who died during the observation period, 86 percent of participants remained in stable housing one year after entering housing. At two years, the housing retention rate for living participants was 81 percent. At year 3, the rate was 77 percent.
• Shelter stays for Denver SIB supportive housing program participants decreased dramatically. When counting all instances of shelter use—including during the day and at night—over a three-year period, those referred to supportive housing had 127 fewer shelter visits compared with their peers in the control group. This represents a 40 percent reduction in shelter stays because of supportive housing.
• Police interactions went down. People referred to supportive housing experienced eight fewer police contacts and four fewer arrests than those who received usual services in the community. This represents a 34 percent reduction in police contacts and a 40 percent reduction in arrests.
• The reductions in jail stays and jail days were notable. In the three years after randomization, participants referred for supportive housing had almost two fewer jail stays and spent an average of 38 fewer days in jail than those who received usual care in the community. This represents a 30 percent reduction in unique jail stays and a 27 percent reduction in total jail days.
• Denver SIB supportive housing program participants used short-term or city-funded detoxification services less often than those in the control group. In the three years after randomization, people referred for supportive housing had four fewer visits to a short-term or city-funded detoxification facility than those who received usual services in the community. This represents a 65 percent reduction in use of detoxification services. The differences between the two groups’ uses of emergency medical services were not statistically significant.

In addition to studying the Denver SIB’s effects on supportive housing participants’ housing stability and criminal justice system outcomes, we studied the program’s effects on people’s use of health care services. 

We also studied the program’s costs and offsets, and we found that approximately half the total per person annual cost of the Denver SIB was offset by cost avoidances in other public services, with some of the biggest avoidances in reduced jail, ambulance, and emergency department costs. Because housing assistance was provided through vouchers funded at the state and federal levels, most of Denver’s costs for SIB supportive services were offset by reductions in costs for local emergency services.

These findings demonstrate the Denver SIB’s remarkable success, and they disrupt the false narratives that homelessness is an unsolvable problem and that people who experience chronic homelessness choose to live on the street. They also show that investment in supportive housing can decrease police interactions and arrests, disrupt jail cycling, and reduce the use of emergency detoxification facilities. Expanding investments in supportive housing could end homelessness, break the homelessness-jail cycle, and shift resources away from policing and other costly emergency services toward services that focus on housing, well-being, and the prevention of negative outcomes for residents and communities.

The web page was revised November 22, 2023. A sentence about the effects of supportive housing on people's use of health care services was removed because a peer-reviewed journal is considering the working paper that discusses those effects for publication. This page will be updated when further publishing information is available.