The research avoided problems of earlier studies of the effects of birth order in that it included the entire population of a fairly closed country with a low rate of emigration. Juvenile delinquency statistics came from Israel's Ministry of Welfare, and data concerning the general population came from other official statistics. The analysis considered youths aged 9 to 16 and the years 1968-1976, with emphasis on the 1973-75 period. Middle-born children had higher delinquency rates than other children of the same family size. When the order of birth was controlled, children from larger families tend to have higher delinquency rates. Finally, the effect of sibling position became stronger as the number of siblings rose. The division of family resources among all the children living at home and the fact that middle-born children always have the largest number of siblings living at home appear to explain these results. Figures, tables, and 46 references. ABI cfw