THE INTRODUCTORY SECTION DISCUSSES PREVIOUS STUDIES ON THE TOPIC DONE IN THE UNITED STATES AND ABROAD. THE STUDY OF BIRTH-ORDER (OR SIBSHIP POSITION) AND ITS BEHAVIORAL CORRELATES HAS BEEN ONE OF INTEREST TO PSYCHOLOGISTS SINCE EARLY IN THE NINETEENTH CENTURY. EARLY FINDINGS INDICATED WITH FEW EXCEPTIONS THE ASSOCIATION OF DELINQUENCY WITH THE FIRST-BORN POSITION, WHILE LATER STUDIES HAVE TENDED TO FIND THAT INTERMEDIATE POSITIONS ARE THE MOST VULNERABLE. THE PRESENT STUDY INVESTIGATES THE RELATIVE REPRESENTATION OF DIFFERENT SIBLING POSITIONS AMONG THE JUVENILE DELINQUENTS IN ISRAEL. THE INSTRUMENT WAS A STATISTICAL DESCRIPTION OF ALL JUVENILES SUBJECTED TO TREATMENT BY THE YOUTH PROBATION SERVICE DURING THE PREVIOUS YEAR. THE PUBLISHED STATISTICS INCLUDED INFORMATION ABOUT THE JUVENILES' FAMILIES AND THEIR POSITION WITHIN THEIR SIBSHIPS. THESE DATA WERE COMPARED WITH GENERAL POPULATION DATA ON THE DISTRIBUTION OF BIRTH ORDERS. RESULTS SHOWED THAT THE HIGHER THE BIRTH ORDER OF A JUVENILE, THE MORE LIKELY HE WAS TO BECOME DELINQUENT. THESE RATES INCREASED FROM LESS THAN 4 PER 1,000 FOR FIRST AND SECOND CHILDREN TO OVER 20 PER 1,000 FOR CHILDREN HOLDING THE NINTH OR HIGHER POSITION. THE FINDINGS ALSO INDICATE THAT THE DELINQUENCY RATE FOR A GIVEN SIBSHIP POSITION IS HIGHER AS THE SIBSHIP BECOMES LARGER INDICATING A LINK BETWEEN DELINQUENCY AND FAMILY SIZE. ALSO NOTED WAS THAT FOR EACH SIBSHIP SIZE, MIDDLE-BORN CHILDREN WERE MORE LIKELY TO BECOME DELINQUENT THAN THE FIRST OR LAST CHILD. IN SUMMARY, IT IS STATED THAT DELINQUENTS TEND TO BE THE MIDDLE-BORN CHILDREN IN THEIR SIBSHIPS. THIS FINDING CORROBORATES SOME OF THE RECENT STUDIES, BUT REFUTES MOST EARLY ONES. (MJW)