THE DELINQUENT POPULATION STUDIED WAS COMPOSED OF 254 JAPANESE JUVENILES PLACED ON PROBATIONARY SUPERVISION AND 181 RECEIVING TREATMENT IN TRAINING SCHOOLS. TREATMENT STAFF MEMBERS RESPONDED TO A QUESTIONNAIRE PERTAINING TO EACH JUVENILE'S BEHAVIOR ATTITUDES, SELF-CONCEPT, WORK EXPERIENCE, FAMILY RELATIONSHIPS, AND CERTIFICATES OR LICENSES OBTAINED DURING TREATMENT/PROBATION. RECIDIVISM WAS DEFINED AS ANY OFFENSE RESULTING IN APPREHENSION BY POLICE. DATA WERE ASSESSED USING MULTIPLE REGRESSION ANALYSIS AND PREDICTIVE ATTRIBUTE ANALYSIS METHODS. FOR PROBATIONERS, THE OFFICER'S EVALUATION OF THE JUVENILE'S ATTITUDES AND BEHAVIORS SHOWED THE HIGHEST CORRELATION WITH RECIDIVISM: ATTITUDE TOWARD AUTHORITY AND SELF-CONCEPT WERE PARTICULARLY SIGNIFICANT IN THE MIDDLE PERIOD OF SUPERVISION, AND ATTITUDE TOWARD OWN LIFE STYLE WAS PARTICULARLY SIGNIFICANT DURING THE LATTER PART OF SUPERVISION. MAJOR FACTORS RELATED TO THESE ATTITUDES INCLUDE PREVIOUS COMMITMENT HISTORY AND FAMILY RELATIONS AND STATUS, AS WELL AS INTERPERSONAL MALADJUSTMENT AND CHARACTER DISORDER. FOR JUVENILES RELEASED FROM TRAINING SCHOOL, DESIRABLE ATTITUDES TOWARD AUTHORITY DURING THE MIDDLE PERIOD AND POOR SELF-CONCEPT DURING THE LATTER PERIOD OF TREATMENT WERE BOTH RELATED TO RECIDIVISM. IT IS SUGGESTED THAT, FOR THIS GROUP OF RECIDIVISTS, ACCEPTANCE OF AUTHORITY AND AN UNREALISTIC AND DISTORTED SELF-CONCEPT MAKE THE DEVELOPMENT OF INSIGHT DIFFICULT AND LEAD TO RECIDIVISM. IT IS SUGGESTED THAT PROBATION WOULD PROVE MOST EFFECTIVE FOR THOSE JUVENILES WHO CAN BE REHABILITATED THROUGH ENVIRONMENTAL ADJUSTMENTS, AND MOST INEFFECTIVE FOR THOSE WITH A LONG HISTORY OF DELINQUENCY. FOR JUVENILES WITH A GREATER COMMITMENT TO DELINQUENCY, TRAINING SCHOOL TREATMENT WILL BE MOST EFFECTIVE IF EMPHASIS IS PLACED ON EDUCATION AND THE CORRECTION OF PERSONALITY DISORDERS. (JAP)