TOPS was a multiyear study that involved more than 10,000 drug users who entered treatment in 1979, 1980, or 1981. They were interviewed when they first entered 37 selected drug abuse treatment programs in the United States. The treatments involved methadone, residential, and outpatient drug-free programs. After examining the nature of drug abuse treatment under these three major modalities, this book describes client sociodemographic characteristics, the nature and severity of drug abuse, and other client behaviors upon entering treatment. Also discussed are the nature and extent of drug abuse and the types of behavior that interfere with productive lives before, during, and after treatment. Abstinence and improvement rates for each modality are presented. An examination of factors affecting post-treatment drug abuse and other behaviors such as criminal activity, employment, depression, and alcohol use focus on the relationship between these outcomes and the clients' pretreatment characteristics and treatment duration. The costs and benefits of drug abuse treatment are considered in terms of its impact on crime reduction. Overall, the evidence shows that treatment of appropriate quality and duration does have positive results, both for drug abusers and for American society, such that it must be a major component of a national drug policy. Chapter tables and figures, 336 references, subject index.