At the Clinic of Forensic Psychiatry in Rostock, Germany, we treat addicted offenders in a closed psychiatric setting. In 2009 we implemented the “Reasoning and Rehabilitation Program” (R & R, Ross & Fabiano, 1986), a cognitive skills program, in our clinic. There are several international studies confirming the efficacy of this training in diminishing recidivism.We examined a sample of 31 inpatients randomly distributed among the experimental (R & R) and the control group. Most of the study participants had committed homicide or other serious violent offenses. Prisoners with schizophrenia, organic mental disorders and mental retardation were excluded from the study. The target skills were assessed by treating psychotherapists, primary nurses and by the patients themselves.Our findings indicated that problem-solving, awareness of consequences, social perspective-taking, cognitive style, the ability to learn by experience, and persistence in the experimental group were significantly improved. The awareness of consequences has changed significantly in the assessment of the treating psychotherapists, the primary nurses, and the offenders themselves.Our current data are similar to our recent work, where we found significant changes in mental flexibility, planning, and problem-solving and positively assessed tendencies in some skills (Wettermann et al., 2012, 2011).Verification of these findings in a larger sample would strengthen the research foundation for this important training to diminish prisoner recidivism.