Objectives Housing First is a supportive housing model for persons with histories of chronic homelessness that emphasizes client-centered services, provides immediate housing, and does not require treatment for mental illness or substance abuse as a condition of participation. Previous studies of Housing First have found reduced governmental costs and improved personal well-being among participants. However, variations in real-world program implementation require better understanding of the relationship between implementation and outcomes. This study investigated the effects of Housing First implementation on housing and substance use outcomes.

Methods Study participants were 358 individuals with histories of chronic homelessness and problematic substance use. Clients were housed in nine scatter-site Housing First programs in New York City. Program fidelity was judged across a set of core Housing First components. Client interviews at baseline and 12 months were used to assess substance use.

Results Clients in programs with greater fidelity to consumer participation components of Housing First were more likely to be retained in housing and were less likely to report using stimulants or opiates at follow-up.

Conclusions Consistently implemented Housing First principles related to consumer participation were associated with superior housing and substance use outcomes among chronically homeless individuals with a history of substance use problems. The study findings suggest that program implementation is central to understanding the potential of Housing First to help clients achieve positive housing and substance use outcomes.