This research explored theoretical aspects underlying the concept of aggression and aspired to implement and evaluate a comprehensive program for violent and aggressive inmates. The program, Aggression Replacement Training (ART), was originally developed by Goldstein, Glick, Reiner, Zimmerman, and Coultry (1987) for aggressive adolescents. The current research adapted the program for use with incarcerated adults and employed 57 males, ages 21-50. The experimental group included 30 subjects; the remaining 27 men comprised the control group. Experimental subjects participated three hours per week in the ten week ART program. One hour per week was devoted to each of the three program components: prosocial skills training; anger management; and dilemma discussion (moral education). Subjects were compared on several pretest and posttest measures including: the Direct Situations Test (DST) (Goldstein et al., 1987) used to assess acquisition of prosocial skills; the Hostility Scale (HOS) and Aggression Scale (AS) (Blackburn, 1974 cited in Brodsky & Smitherman, 1983) used to measure subjects'' feelings of anger and aggression; and the Sociomoral Reflection Measure (SRM) developed by Gibbs, Widaman, and Colby (1982) to determine subjects'' level of moral reasoning. The Generalized Situations Test (GST) was administered as a posttest only and served to measure transfer of training for prosocial skills. Weekly behavioral ratings were to be conducted by caseworkers on inmates in the treatment program. Results provide partial support for hypothesis that skills training enhances inmates'' prosocial behavior. A multiple analysis of variance revealed a significant difference between groups on the DST, F(1,46) = 2.14, p =.04. Inmates in the treatment program showed significant improvement for the skill Expressing a Complaint, F(1, 55) = 8.01, p =.006. Comparison of scores on the GST (given only as a posttest) suggest the possibility that treatment subjects exhibit transfer of training for the skill Expressing a Complaint t(,55) = 2.60, p =.01. However, examination of actual means reveals only a slight advantage in favor of the experimental group. Contrary to predictions, inmates in the ART program demonstrate a decrease in level of moral reasoning following participation in treatment, F(1,53) = 4.79, p =.03. No other analyses yielded statistically significant differences. Behavioral ratings were returned sporadically and were often incomplete rendering proposed analysis impossible. Clinical observations of inmates in the program made by this researcher and her colleague include increased cooperation and improved interactions between inmates, less negativity, increased willingness to attempt new behaviors in group and practice these behaviors outside of group, all of which are considered to be foundations for changes in behavior and prerequisites for behavioral improvement and continued treatment. It was concluded that a treatment intervention of only ten weeks may not provide enough time or exposure to the program elements to have a measurable impact on adult inmates. This researcher believes that the minimal changes evidenced by subjects mark the beginning of the change process and that more intensive involvement in treatment is required for this population.