This paper compares the economic costs and benefits of a modified therapeutic community (TC) approach to treating homeless mentally ill substance abusers as compared with "treatment as usual." The study considered employment, criminal activity, and utilization of health care services as outcome measures and found that while the economic cost of the average TC episode was $20,361 the average economic benefit of such an episode was $305,273.  The authors note that "The incremental economic benefit per modified TC client (relative to TAU) was $273,698, resulting in a net benefit per modified TC client of $253,337 and a benefit–cost ratio of 13:1. Adjusting for extreme outlier observations, the incremental economic benefit estimate was $105,618, net benefit was $85,257, and the benefit–cost ratio was 5.2." 

French, M.T., McCollister, K.E., Sacks, S., McKendrick, K. & De Leon, G. (2002). Benefit cost analysis of a modified therapeutic community for mentally ill chemical abusers. Evaluation and Program Planning, 25: 137-148. DOI: 10.1016/S0149-7189(02)00006-X