This study identifies the dynamic variables of recidivism in a sample of drug-dependent inmates released from Burgos prison (Spain) in the third prison grade to finish their prison sentence in a Therapeutic Community. The documentary sources, consulted for collecting information of 120 subjects, males and between 21 and 40 years (age of release), were the prison record, the classification and treatment protocol, and the social record. Applying a descriptive statistical analysis with contingency tables, the characteristics of the variables that showed higher percentages of recidivism were: lack of work habits, HIV infectious disease, higher scores in extraversion, finalizing the treatment with expulsion or abandonment, and shorter stay in a therapeutic community. These results suggest that relapse prevention can achieve positive results, if we achieve a significant influence on these variables through the penitentiary treatment.