Comprehensive costing of human services remains an understudied issue in evaluating health and social services. Evaluations done to date have considered either only some of the services offered to clients or restricted the examination to costs borne by programs. Most studies to date have been conducted in the United States and Britain, countries that have different systems of health and social services than Canada. This article presents a case study of the use of a “comprehensive costing approach" in a Canadian context. The approach examines the full range of costs of health and social services and other supports associated with assisting a person with severe and persistent mental illness to live in the community. The case study represents a pilot program (funded by the Ministry of Health in Ontario) to provide specialized support services for a consumer to live in the community. Cost comparisons developed around the initiation of the pilot program in the present evaluation examined the initial months of the consumer in the program and a period prior to entering the program when the consumer was receiving standard care in the community including a period of hospitalization. Costs were compared according to different domains such as accommodation, social benefits and health and social services. Perspectives of program planners on the impact of costing evaluations for a case study are provided, followed by limitations and future directions for the methodology.