A STUDY OF 80 INCARCERATED JUVENILE DELINQUENTS MATCHED THEM WITH A SAMPLE OF 77 NONINCARCERATED DELINQUENTS. A TOTAL OF 36.25 PERCENT OF THE FORMER HAD COMMITTED SERIOUS, VIOLENT OFFENSES COMPARED TO 6.49 PERCENT OF THE LATTER. MEDICAL HISTORIES OF THE TWO GROUPS WERE COMPARED. A TOTAL OF 72 PERCENT OF THE INCARCERATED JUVENILES HAD BEEN TREATED FOR ACCIDENTS COMPARED TO APPROXIMATELY 71 PERCENT OF THE NONINCARCERATED JUVENILES. HOWEVER, THE TWO GROUPS DIFFERED SIGNIFICANTLY IN THE TYPE OF INJURIES RECEIVED. THE INCARCERATED DELINQUENTS RECEIVED 62.3 PERCENT OF THEIR TREATMENT FOR HEAD AND FACE INJURIES AS OPPOSED TO 44.6 PERCENT FOR THE NONINCARCERATED. CHILD ABUSE WAS ALSO ENCOUNTERED MORE FREQUENTLY AMONG THE INCARCERATED (10.4 PERCENT VERSUS 3.6 PERCENT). PERINATAL DIFFICULTIES WERE MUCH MORE FREQUENT AMONG THE INCARCERATED GROUP: 36.6 PERCENT VERSUS 8 PERCENT. IT CAN BE SEEN THEN THAT PERINATAL DIFFICULTIES, HEAD INJURIES, AND MORE FREQUENT CHILD ABUSE DISTINGUISH THE INCARCERATED DELINQUENTS FROM THE NONINCARCERATED GROUP. THE SAME TENDENCIES WERE SEEN IN A STUDY OF TWO GROUPS OF INCARCERATED JUVENILE BOYS. THOSE WHO WERE EXTREMELY VIOLENT AND INCARCERATED IN SPECIAL SECURITY UNITS SHOWED HISTORIES OF SIGNIFICANTLY GREATER PERCENTAGES OF PERINATAL DIFFICULTIES, HEAD INJURIES AND ABUSE THAN DID THE REGULARLY INCARCERATED DELINQUENTS. IT IS CONCLUDED FROM THESE STUDIES THAT ANY ONE OF THESE CONDITIONS BY ITSELF IS NOT ENOUGH TO CAUSE SERIOUS, VIOLENT DELINQUENCY AMONG JUVENILES. REFERENCES ARE INCLUDED. (STB)