It has been commonly assumed that forced substance abuse treatment of substance-abusing offenders is counterproductive, because it undermines client initiative, self-determination, and self-respect, which are believed essential to progress in treatment. Contrary to expectations, however, a substantial body of evidence shows that legally mandated substance abuse clients perform as well as, or better than, voluntary clients on various measures of treatment retention, abstinence, and psychosocial functioning across a diverse range of settings. Diversionary programs for substance-abusing offenders tend to rely more on behavioral principles of negative reinforcement than punishment. In the strictest sense, "punishment" is defined as any consequence of a behavior that reduces the likelihood that the behavior will be repeated, or repeated at the same rate, in the future. "Negative reinforcement," on the other hand, is defined as the removal of a sanction, contingent on a target behavior, which has the effect of increasing that behavior. Although punishment may, under some circumstance, be a relatively inefficient means of controlling behavior, negative reinforcement can be effective and enduring. Punishment can also be effective, but only if negative sanctions are delivered reliably, quickly, and with sufficient intensity. For coercive treatment to work most effectively, close monitoring of clients and appropriate coordination of functions between mental health professionals and responsible correctional officials is essential. The scope of disclosure should typically be limited to attendance information, the prognosis of the client, a brief description of the client's progress in treatment, and a short statement on the frequency and nature of relapse to substance use, if any. 16 references