USING QUAY'S TYPOLOGY, THREE GROUPS OF 12 MEMBERS EACH OF ADOLESCENT PSYCHOPATHIC, NEUROTIC, AND SUBCULTURAL DELINQUENT MALES AND A MATCHED NONDELINQUENT CONTROL GROUP INDIVIDUALLY WERE ADMINISTERED KOHLBERG'S STRUCTURED MORAL DILEMMAS, TWO PIAGETIAN TASKS OF COGNITIVE DEVELOPMENT (PENDULUM AND BALANCE), AND AN ADAPTATION OF FLAVELL'S ROLE TAKING TASK. JUVENILE DELINQUENTS WERE CHOSEN FOR STUDY FROM A POOL OF APPROXIMATELY 120 INSTITUTIONALIZED DELINQUENT BOYS. PSYCHOPATHIC DELINQUENTS WERE FOUND TO BE MORE IMMATURE IN THEIR LEVEL OF MORAL DEVELOPMENT THAN ALL THE OTHER GROUPS; THE OTHER GROUPS DID NOT DIFFER FROM ONE ANOTHER. PSYCHOPATHIC DELINQUENTS WERE SIGNIFICANTLY MORE CONCRETE IN THEIR THINKING ON COGNITIVE TASKS THAN ALL OTHER GROUPS; THE OTHER GROUPS EXHIBITED SIGNS OF EARLY FORMAL OPERATIONAL THINKING. PSYCHOPATHIC AND, TO A LESSER EXTENT, NEUROTIC DELINQUENTS WERE DEFICIENT IN ROLE TAKING, AS COMPARED WITH SUBJECTS IN CONTROL AND SUBCULTURAL GROUPS WHO DID NOT DIFFER FROM ONE ANOTHER. THE FINDINGS PROVIDE EVIDENCE AGAINST VIEWING DELINQUENCY AS A UNITARY SYNDROME OF DEVIANCE. FROM A PRACTICAL STANDPOINT, THE ISOLATION OF DELINQUENT SUBGROUPS AND THEIR CORRELATES HAS SIGNIFICANT IMPLICATIONS FOR THE DESIGNING OF CORRECTIONAL PROGRAMS MORE APPROPRIATELY ORIENTED TO THE DIFFERENTIAL COGNITIVE AND PERSONALITY STRUCTURES OF JUVENILE DELINQUENTS. SUPPORTING DATA AND REFERENCES ARE PROVIDED. THE STUDY INSTRUMENTS ARE NOT INCLUDED. (AUTHOR'S ABSTRACT MODIFIED--DEP)