THE STUDY INVOLVED A GROUP OF MALE ADULT INMATES OF A MEDIUM SECURITY PRISON, AT THE BEGINNING OF INCARCERATION, AND AT THE TIME OF RELEASE. THE POPULATION CONSISTED OF FOUR GROUPS OF 30 INMATES EACH. GROUP A, THE EXPERIMENTAL GROUP, WAS EVALUATED AT ADMISSION, ONE MONTH, TWO MONTHS, AND EIGHT MONTHS AT A MEDIUM SECURITY PRISON. GROUPS B AND C WERE TESTED AT FIFTEEN MONTHS AND TWENTY MONTHS AT THE SAME INSTITUTION, GROUP D, THE CONTROL GROUP, WAS TESTED AT ADMISSION AND AT THE COMPLETION OF EIGHT MONTHS AT A MAXIMUM SECURITY PRISON. THE INSTRUMENTS USED TO EVALUATE GROUPS A, B, AND C WERE THE INDEX OF ADJUSTMENT AND VALUES, THE DE SCALE OF THE CALIFORNIA PSYCHOLOGICAL INVENTORY, AND THE RATING SCALE FOR INSTITUTIONAL ADJUSTMENT. AN ANALYSIS OF THE FINDINGS INDICATES THAT THE GROUP STUDIED FOR EIGHT MONTHS AT THE MEDIUM SECURITY PRISON IMPROVED CONSIDERABLE. THERE WAS A GREATER ABILITY TO ACCEPT ONESELF, A LESSER DEGREE OF PERSONAL MALADJUSTMENT AND A LOWERING OF THE POTENTIAL TOWARD CRIME AND DELINQUENCY. FURTHER, THERE WAS INCREASED ADJUSTMENT TO THE INSTITUTION AFTER THE FIRST MONTH. (AUTHOR ABSTRACT)