No single accepted method or setting exists for the treatment of substance abuse—alcohol and other drug-abuse disorders. Treatment is offered in specialty units of general and psychiatric hospitals, residential facilities, halfway houses, outpatient clinics, mental-health centers, jails and prisons, and the offices of private practitioners.

In the United States during the 1970s and 1980s, drug abusers were commonly treated in programs distinct from those serving alcoholics. By the 1990s, the two treatment systems were merged; in 1991, of the estimated 11,000 substance-abuse treatment programs in the United States, 79 percent reported that they served both drug and alcohol abusers. Some 88 percent were enrolled in outpatient programs. Another 10 percent were in residential facilities. Only 2 percent were hospital inpatients.

The cost of treatment varied greatly depending on setting. In the early 1990s, hospital inpatient care was the most expensive on a daily basis ($300-...