This chapter reviews the therapeutic community (TC) approach, as used in the criminal justice field, as an attempt to better understand the success that has been achieved with this treatment model. The chapter describes some basic principles of the TC and discusses concepts about change that are actualized in the TC. In conclusion, this chapter reviews the experiences of the Delaware Department of Correction in using the TC as a method of treatment for those incarcerated with chronic substance abuse issues. (PsycINFO Database Record (c) 2019 APA, all rights reserved)