This study was undertaken to articulate program impact theory for the Comprehensive Home Option of Integrated Care for the Elderly (CHOICE) program. The study showed that CHOICE combines elements found in a traditional Health Maintenance Organization with elements and process components drawn from primary care and case management to deliver a broad range of home support, day program, and social and health services to its participants and their informal care givers. In doing so the program provides participants with a level of comprehensive, coordinated care not possible within the traditional community based health and social service delivery system.