THE STUDY WAS SPECIFICIALLY CONCERNED WITH DELINQUENT ADOLESCENTS WHOSE MMPI PROFILES CONTAINED ELEVATIONS ON CLINICAL SCALES 4 OR 4 AND 9 (CODE TYPE 4, 4-9, 9-4) AND DELINQUENT ADOLESCENTS MANIFESTING ELEVATIONS ON SCALES 4 AND 8 (CODE TYPE 4-8, 8-4). FACTORS AND AREAS OF FUNCTIONING INVESTIGATED IN THE COURSE OF THE COMPARATIVE STUDY INCLUDED PEER AND AUTHORITY RELATIONSHIPS, INDIVIDUAL PERSONALITY AND BEHAVIORAL TRAITS, DEMOGRAPHIC AND DYNAMIC INFORMATION ON FAMILIES, ACTING OUT HISTORY, INTELLECTUAL LEVEL, ACADEMIC PERFORMANCE, AND RESPONSE TO TREATMENT. AN EFFORT WAS MADE TO INTEGRATE RELEVANT EMPIRICAL AND THEORETICAL LITERATURE ON PSYCHOPATHY, DELINQUENCY, AND MMPI-BASED ACTUARIAL RESEARCH. ADOLESCENTS IN THE CODE TYPE 4-9 GROUP WERE TYPICALLY REFERRED FOR TREATMENT BECAUSE OF DEFIANCE, IMPULSIVITY, PROVOCATION, OR CONSTANT CONFLICT WITH THEIR PARENTS OVER MISBEHAVIOR. THE SYMPTOM PATTERN DEMONSTRATED FOR ADOLESCENTS IN THE CODE TYPE 4-8 GROUP WAS CLEARLY ONE OF IMMATURITY COUPLED WITH NARCISSISM. THE STUDY OF THESE ADOLESCENTS WAS CONDUCTED AT LINCOLN HALL, A RESIDENTIAL TREATMENT CENTER IN NEW YORK CITY FOR MALE ADOLESCENTS WHO HAD BEEN COURT-ADJUDICATED AS EITHER JUVENILE DELINQUENTS OR PERSONS IN NEED OF SUPERVISION. A TOTAL SAMPLE OF 60 SUBJECTS FOR EACH CODE TYPE WAS ESTABLISHED. ALL SUBJECTS WERE IN RESIDENCE AT LINCOLN HALL, WITH LENGTH OF TIME IN THE PROGRAM RANGING FROM 2 TO 15 MONTHS. VARIOUS INSTRUMENTS WERE USED TO ASSESS PERSONALITY AND DIFFERENTIAL PATTERNS OF ADOLESCENT AND DELINQUENT PERSONALITY ADJUSTMENT. DATA ANALYSIS COVERED 362 ITEMS DESIGNED TO DIFFERENTIATE BETWEEN CODE TYPE 4-9 AND CODE TYPE 4-8 DELINQUENTS. THERE WERE 67 SIGNIFICANT REPLICATED DIFFERENCES BETWEEN THE TWO CODE TYPE GROUPS. IN GENERAL, FINDINGS SUBSTANTIATED THE EXISTENCE OF DELINQUENCY SUBTYPES AND CONFIRMED THE EFFICACY OF THE MMPI IN DIFFERENTIAL DIAGNOSIS. FURTHER INFORMATION ON THE STUDY AND INSTRUMENTS USED TO OBTAIN DATA ARE CONTAINED IN APPENDIXES. SUPPORTING DATA AND REFERENCES ARE PROVIDED. (DEP)