Objective: The purpose of this study, which is part of a larger clinical trial, was to examine the cost-effectiveness of case management for individuals treated for substance abuse in a residential setting. Method: Clients who agreed to participate were randomly assigned to one of four study groups. Two groups received face-to-face case management and one telecommunication case management, and the fourth was the control group. Results: Using a ratio of cost to days free from substance abuse, the case management groups were less cost-effective than the control group at 3 months, 6 months, and 12 months. The telecommunication case management was least cost-effective of the three case management conditions. Conclusion: Results from the analysis revealed case management is not cost-effective as a supplement to traditional drug treatment over a 12-month follow-up period. (Contains 6 tables and 2 figures.)