For three decades, NIDA has conducted several large studies to advance scientific knowledge of the outcomes of drug abuse treatment as typically delivered in the United States. These studies collected baseline data from over 65,000 individuals admitted to publicly funded treatment agencies. They included a sample of TC programs and other types of programs (i.e., methadone maintenance, out-patient drug-free, short-term inpatient, and detoxification programs). Data were collected at admission, during treatment, and in a series of followups that focused on outcomes that occurred 12 months and longer after treatment.

These studies found that participation in a TC was associated with several positive outcomes. For example, the Drug Abuse Treatment Outcome Study (DATOS), the most recent long-term study of drug treatment outcomes, showed that those who successfully completed treatment in a TC had lower levels of cocaine, heroin, and alcohol use; criminal behavior; unemployment; and indicators of depression than they had before treatment.