It is well documented that homeless individuals with severe mental illness (SMI) are in frequent contact with multiple public systems including housing, health, criminal justice, income assistance and various community-based programs. However, this subpopulation of the homeless continues to experience significant unmet needs. This report examines preliminary findings from British Columbia's Homeless Intervention Project, an interagency collaboration designed to improve outcomes for adults with SMI who are chronically homeless. Administrative data from three provincial ministries were used to examine a variety of outcomes for 362 participants with histories of criminal justice involvement. Comparisons of the pre-enrollment period (2 years) and post-enrollment period (6 or 12 months) indicate significant improvements in health and social service involvement and reductions in offending. These findings suggest that interagency collaboration, particularly co-location and sharing of information and administrative oversight, can result in better outcomes for this hard-to-serve population than when agencies are working in isolation.