Compulsory treatment potentially offers a cost-effective and rehabilitative alternative to incarceration for substance-user offenders. However, the compatibility of harm-reduction principles and compulsory substance-user treatment initiatives is unclear. First, the historical record suggests that policy and legislative changes promoting diversion to treatment are typically not followed up by administrative, fiscal, and evaluative support. Moreover, cost-saving arguments underlying past programs may be inadequate to cope with concerns about civil liberties raised by compulsory treatment practices. Second, empirical evidence suggests that there may be a fundamental incompatibility between attitudes endorsing compulsory treatment and attitudes endorsing harm reduction. Finally, empirical claims about the relative efficacy of mandated versus nonmandated substance-user treatment are plagued by conceptual and methodological problems. These arguments suggest that compulsory substance-user treatment and harm reduction may not be as compatible as is commonly believed. Consequently, caution is warranted in moving toward a widespread adoption of compulsory treatment policies. [Translations are provided in the International Abstracts Section of this issue.]