ONE GROUP CONSISTED OF 50 CONSECUTIVE CASES INVOLVING BOYS BETWEEN 14 AND 18 YEARS OF AGE WHO HAD BEEN FOUND GUILTY OF VIOLENT OFFENSES (ROBBERY, SEXUAL AND NONSEXUAL ASSAULTS, AND HOMICIDE). THE COMPARISON GROUP COMPRISED A RANDOM SAMPLE OF BOYS IN THE SAME AGE GROUP WHOSE PAST AND PRESENT OFFENSES WERE AGAINST PROPERTY (BREAKING AND ENTERING, STEALING, AND LARCENY OF MOTOR VEHICLES). BY DESIGN, THE COMPARISON GROUP EXCLUDED ANYONE WITH AN ESTABLISHED RECORD OF VIOLENCE. BOTH GROUPS WERE COMPARED IN TERMS OF VARIABLES SUCH AS PERSONAL-SOCIAL ATTRIBUTES, RELATIONSHIP WITHIN FAMILY, NEUROLOGICAL CHARACTERISTICS, BIRTH HISTORY, SELF-IMAGE, DIMENSIONS OF PERSONALITY, AND AGGRESSION. A SPECIAL SCALE CONSISTING OF APPROXIMATELY 80 ITEMS WAS DEVELOPED IN AN EFFORT TO MEASURE AGGRESSION IN ITS VARIOUS FORMS. DIFFERENCES BETWEEN THE TWO GROUPS WERE NOT SIGNIFICANT EXCEPT WITH REGARD TO THEIR SUPERVISION, THEIR RELATIONSHIP WITH FATHERS, THE NEUROTIC DISTURBED DIMENSION OF PERSONALITY, AND THE FACT THAT PROPERTY OFFENDERS WERE MORE PRECOCIOUS THAN VIOLENT OFFENDERS. LITTLE SUPPORT WAS FOUND FOR THE VIEW THAT YOUNG OFFENDERS BEFORE COURTS FOR AGGRESSIVE OFFENSES HAVE DISTINCTLY VIOLENT CRIMINAL HISTORIES. SUPPORTING DATA AND REFERENCES ARE INCLUDED.