THE MINNESOTA MULTIPHASIC PERSONALITY INVENTORY (MMPI) AND AN INFORMATION QUESTIONNAIRE WERE USED IN THE STUDY. PATIENTS WERE DIVIDED INTO OVERCONTROLLED PERSONALITY TYPE OR UNDERCONTROLLED PERSONALITY TYPE BASED ON ANAMNESTIC DATA AND OVERCONTROLLED-HOSTILITY SCORES. THE OVERCONTROLLED GROUP SHOWED A BETTER ADJUSTED MMPI PROFILE; SCORED HIGHER ON SCALES REFLECTING REPRESSION, DENIAL, CONSCIENCE, AND INHIBITION OF AGGRESSION; AND SCORED LOWER ON SCALES REFLECTING IMPULSIVENESS AND ACTING-OUT HOSTILITY. HOWEVER, WHEN THESE OVERCONTROLLED PATIENTS ENGAGED IN ASSAULTIVE BEHAVIOR, THEY TENDED TO COMMIT EXTREMELY VIOLENT CRIMES. IN CONTRAST, THE UNDERCONTROLLED PERSONS SCORED LOWER ON SOCIAL ADJUSTMENT SCORES AND SHOWED LOW INHIBITION TOWARD AGGRESSION. HOWEVER, THEIR ASSAULTIVE ACTS WERE MORE FREQUENT AND LESS VIOLENT. A THERAPEUTIC PROGRAM FOR OVERCONTROLLED TYPES COULD FOCUS ON ENCOURAGING THEM TO UNCOVER AND ASSUME RESPONSIBILITY FOR PROBLEMS BEFORE TENSIONS ACCUMULATE AND EXPLODE, AND ON TEACHING THEM ALTERNATIVE WAYS OF DEALING WITH HOSTILE FEELINGS. A TABLE AND 18 REFERENCES ARE INCLUDED.