This booklet—a complement to NIDA’s Principles of Drug Addiction Treatment: A Research-Based Guide—is intended to describe the treatment principles and research findings that have particular relevance to the criminal justice community and to treatment professionals working with drug abusing offenders. It is divided into three main sections: (1) research findings on addicted offenders distilled into 13 essential principles, (2) a series of frequently asked questions (FAQs) about drug abuse treatment for those involved with the criminal justice system, and (3) a resource section that provides Web sites for additional information.