THE SAMPLE POPULATION CONSISTED OF 55 JUVENILES WHO WERE HOSPITALIZED IN THE DELINQUENCY UNIT OF THE ILLINOIS STATE PSYCHIATRIC INSTITUTE FOR A MINIMUM OF 13 WEEKS IN THE STUDY PERIOD 1969-74. THE DATA WERE OBTAINED THROUGH INTERVIEWS, INVENTORIES, SELF-REPORT QUESTIONNAIRES, OBSERVATIONS AND IMPRESSIONS OF OTHERS, REGULAR QUANTIFIED MEASURES OF ANTISOCIAL BEHAVIOR IN THE UNIT, AND PSYCHOLOGICAL TESTING. THE DATA WERE THEN STATISTICALLY ANALYZED, REVEALING FOUR PSYCHODYNAMIC TYPES. THE IMPULSIVE DELINQUENT AS THE MOST OBVIOUSLY DISTURBED TYPE SHOWS CONSIDERABLE VIOLENT AND NONVIOLENT ANTISOCIAL BEHAVIOR. HIS DELINQUENCY DERIVES FROM A PROPENSITY FOR ACTION AND IMMEDIATE DISCHARGE. THE NARCISSISTIC DELINQUENT SEES HIMSELF AS WELL ADJUSTED AND NOT DELINQUENT THOUGH PARENTS AND STAFF CHARACTERIZE HIM AS RESISTANT, CUNNING, MANIPULATIVE, AND SUPERFICIAL. BECAUSE OF HIS EXAGGERATED SELF-WORTH, HE TENDS TO USE OTHERS FOR HIS OWN NEEDS. ESPECIALLY TO HELP REGULATE HIS SELF-ESTEEM. THE DEPRESSED DELINQUENT SHOWS SCHOOL INITIATIVE, IS LIKED BY THE STAFF, AND TRIES TO COOPERATE WITH THE STAFF THERAPEUTICALLY. HE TENDS TO DISPLAY STRUCTURALIZED OR NEUROTIC CONFLICTS FROM WHICH DELINQUENT BEHAVIOR SERVES AS A RELIEF. THE BORDERLINE DELINQUENT IS A PASSIVE, EMOTIONALLY EMPTY, AND DEPLETED PERSON WHO IS NOT WELL LIKED AND WHOSE FUTURE SEEMS PESSIMISTIC. HIS DELINQUENT BEHAVIOR RESULTS FROM AN EFFORT TO PREVENT PSYCHOTIC DISINTEGRATION OR FUSION AND TO RELIEVE HIMSELF OF INTERNAL DESOLATION. THESE PSYCHOLOGICAL SUBGROUPS CONTRIBUTE TO THE UNDERSTANDING OF ADOLESCENT DELINQUENCY REGARDLESS OF AGE, SEX, SOCIOECONOMIC STATUS, OR RACE AND ENRICH PSYCHOTHERAPEUTIC INTERVENTIONS. THE ARTICLE CONTAINS NATIONAL STATISTICAL CHARTS AND A BIBLIOGRAPHY. (AUTHOR ABSTRACT MODIFIED--SAJ)