The program's goals are abstinence from drug use and improvement in the quality of life. The program's theoretical model is based on social learning theories. The intervention emphasizes positive reinforcement of prosocial and alternative- to-drug-use behaviors. The program teaches inmates the social skills necessary to control their behavior, provides basic education and professional training, stimulates and reinforces activities as alternatives to drug consumption, improves relationships with family members, and emphasizes good health practices. The program is structured in progressive periods that gradually confer greater autonomy. For those who have completed the program up until December 31, 1993, 67 percent have maintained abstinence; 28 percent had some relapse and resorted to outpatient treatment; only 6 percent failed by returning to regular drug abuse. Only 7 percent returned to prison for a new offense. These findings show that such a program, when it is given priority and properly funded, can positively impact the lives of its participants. 2 tables and 13 references