Westchester TASC is one of over 40 TASC programs designed to provide a formal mechanism for linking the criminal justice system with substance abuse treatment resources. To meet the needs of a large county with a decentralized criminal justice system, Westchester TASC adopted a multisite case management approach. Tracking of all clients involved in treatment is centralized. Between August 1979, and June 1980, Westchester TASC accepted nearly 400 clients, at least half of whom were still active at the end of June 1980. Successful terminations comprised 8.3 percent of all outcomes; failures, 63.7 percent; and neutral terminations, 28 percent. As more clients complete a full year or more of treatment, the proportion of successes should increase. Many of the program's clients have been seriously involved with both substance abuse and the criminal justice system. TASC has been generally accepted as a valuable resource to the criminal justice system. It has provided legitimacy to conditional discharges, and through its intensive monitoring system, it has also improved the quality of conditional discharges. TASC has also developed successful relationships with treatment programs. A cost analysis of Westchester TASC reveals that it is approaching cost effectiveness in that administrative costs are low, that its costs are close to the median national cost per TASC client, and that a possibility exists for short-term TASC cost benefit in the future. The program's current information system satisfied both process and documentation requirements. Extensive tables are provided.