A sample of 50 first offender prison inmates aged 16 to 20, who were considered at the time of their admission to have the potential for adequate institutional adjustment, were subjected to an intensive psychotherapeutic counseling program for their entire incarceration. The conceptual basis of the program was that institutionally adjusted young inmates, although they may be receptive to therapeutic intervention, often pass through the system with their mental health problems unaddressed. Due to their record of presenting very few administrative problems they are seldom referred to the professional treatment staffs and are released back into the community with the same problems they possessed at admission. Minnesota Multiphasic Personality Inventory (MMPI) pretest and posttest results of the youths were compared to MMPI pre-post tests of a control group of similarly selected young prisoners. The controls (nontreatment) individuals demonstrated no pre-post significant mean scale changes on their MMPI test results, whereas the experimental members presented significant mean scale improvement on 10 of the 15 clinical and additional MMPI scales employed in the study. The treatment sample produced significant improvement on measures of anxiety, depression, overconcern with physical functioning, social alienation, antisocial life style, social prejudice, sense of responsibility, personal adaptability, attitude toward law and order, and the potential to continue criminal activity upon release from incarceration. As positive changes in the personality and social adaptation measures demonstrated by the treatment sample were considered to be subject to regression, further reinforcement from community-based resources would be required if a significant long-range success rate for the treatment sample were to be achieved. Several tables and 10 references are provided. (Author abstract modified)