The article considers the links between problem drug use and crime, the characteristics of effective treatment for problem drug users, the effectiveness of coerced treatment, and the practical obstacles in bridging the gap between criminal justice and treatment services. A substantial body of research documents that a wide range of treatment services are efficacious and cost effective. The article asserts the following: (1) maintenance prescribing of both methadone and heroin emerges well in evaluations as a way of reducing illicit opiate use and related offending; (2) pharmaceutical treatment for dependency on cocaine and other stimulants tends to emerge poorly, but other treatments, including counseling and alternative therapies, are efficacious and cost effective; (3) for treatment to be effective, users must be retained in treatment for a minimum of 3 months; (4) the human qualities of drug user treatment staff are an important variable in determining success; and (5) treatment approaches are likely to be most effective when they are delivered in a positive and supportive environment, and when they provide incentives to engage and hold clients in treatment. Figure, table, references