Background: In 2012, the Los Angeles County Department of Health Services (DHS) created the Housing for Health (HFH) initiative, which seeks to reduce homelessness, prevent unnecessary use of health care resources, and improve health. This project seeks to assess whether HFH achieves these objectives. Methods: We use 2010-2017 linked administrative data from HFH and seven county agencies in housing, health, social, and criminal justice sectors. Anonymized identifiers allow for longitudinal analyses and identification of individuals across multiple data systems. Our statistical approach uses difference-in-difference regressions, comparing HFH clients to a matched comparison sample created using propensity scores. Results: During the study period, 2,979 HFH clients initiated case management; 1,719 were housed. 40.7% of clients identified as African-American; 27.3% as Hispanic; and 20.5% as White. The average client age was 50; nearly two-thirds were male. On average, HFH clients were homeless for nearly 6 years before program participation. Of clients who moved in by June 2016, the 12-month housing retention rate was 94.3%. Preliminary results indicate that the number of health care visits decreased by 27.8% from one year before to one year after housing (65.8% decrease in emergency room visits; 57.5% decrease in inpatient visits). Additional analyses, including service utilization changes in other sectors and a comparison of HFH clients to a matched sample, will soon be completed and findings will be presented at the conference. Conclusions: Our preliminary findings demonstrate HFH's effectiveness at stably housing Los Angeles County's chronically homeless population and dramatically reducing unnecessary health care resource utilization.