The data indicated that families with adolescents produced a disproportionate amount of delinquency, and that on an individual level, having a high-rate delinquent as an older or younger sibling is a significant predictor of juvenile delinquency. However, there is no evidence that families specialize in particular types of delinquency. Sibling composition was found to be more relevant than family structure (single- versus two-parent); an increased number of male siblings corresponded to higher male and lower female offending rates. Thus, the author suggests that sibling, as well as parental, influences should be considered when investigating juvenile delinquency. 5 tables, 1 appendix, 21 footnotes, and 31 references