The TC approach recognizes the high proportion of drug abusers among people arrested and the even higher proportion of drug abusers among those incarcerated. Although drug-using offenders crowd prisons and are also responsible for a disproportionate amount of crime, in-custody drug treatment programs do not always receive priority. In the Federal prison system, drug treatment has been sporadic and slow in coming, but progress has been made. About 30 percent of Federal prisoners with moderate to severe drug problems are treated in residential TCs, and those with less severe drug problems also receive services. In addition, the Federal Bureau of Prisons provides for continuity of drug treatment after release. Treatment for drug abusers in jails is more limited than in prisons. Several TC programs are described to illustrate the benefits of the TC approach. 27 notes, 3 tables, and 1 photograph