THE STUDY EXAMINES THE CHARACTERISTICS OF INSTITUTIONAL CLIMATES FOR YOUNG PRISONERS WITH ADVANCED CRIMINAL TENDENCIES (CLASS YB INMATES), AND CORRELATES INSTITUTIONAL CLIMATES WITH GROUPS OF INMATES AND WITH TREATMENT. A CORRECTIONAL INSTITUTIONS ENVIRONMENT SCALE, DEVELOPED BY E.A. WENK, IS USED AS A MEASURING DEVICE. THE SAMPLE CONSISTED OF 503 CLASS YB INMATES, 552 YOUNG INMATES WITH NO ADVANCED CRIMINAL TENDENCIES (CLASS YA INMATES), AND 520 ADULT (CLASS B) INMATES. THE PRISONERS USED AS SUBJECTS REPRESENTED SIX PRISONS. FINDINGS INDICATE THAT INSTITUTIONAL CLIMATES FOR THE CLASS YB PRISONERS COULD BE DESCRIBED AS DISCIPLINARY, WHILE THE CLIMATES FOR THE CLASS YA PRISONERS WERE THERAPEUTIC AND EDUCATIONAL. CLASS YB INMATES SHOWED FAIRLY STRONG GROUP COHESIVENESS, BUT THEY SELDOM DEVELOPED LARGE GROUP RELATIONSHIPS; THEY ALSO HAD WEAK PSYCHOLOGICAL TIES IN GROUP ACTIVITIES. RESULTS SUGGEST THAT THE CORE OF INSTITUTIONAL LIFE AFFECTING THE MORALE OF INMATES WAS CLOSELY CONNECTED WITH THOSE INSTITUTIONAL CLIMATES IN WHICH INMATES PARTICIPATED POSITIVELY IN PROGRAMS. A STRONG GROUP COHESIVENESS EVIDENCED BY CLASS YB INMATES WAS NOT RELATED WITH GOOD RESULTS IN LIVING ATTITUDES, WORK ACHIEVEMENT, AND OBSERVATION OF DISCIPLINARY RULES. FUTURE PROPOSALS ARE MADE CONCERNING THE TREATMENT OF CLASS YB PRISONERS, WHICH INCLUDE MOVING AWAY FROM THE DISCIPLINARY CLIMATE TO THE THERAPEUTIC CLIMATE, INTEGRATION AND REGULATION OF GROUPS, AND EMPHASIS ON LIVING GUIDANCE AS A CORE METHOD FOR TREATMENT. (DAG)