The data used in this study were obtained from 675 boys and their caretakers who were in grades 9 and 10 during Wave 4 of the study, the first point at which information on firearms ownership was collected. The results showed that 10 percent of the sample owned guns; 27 percent owned guns only for hunting and target shooting, 30 percent for protection, and 10 percent for both reasons. Protection gun owners were more likely than others to be involved in activities that threatened their own and others' safety. They were more likely to carry sawed-off long guns, they carried guns at substantially higher rates, and they used guns more frequently to commit crimes. They were also more likely to belong to gangs, to sell drugs, and to commit both minor and street crimes. The delinquency rate of sport gun owners was only slightly higher than that of boys who did not own guns. 4 tables, 12 notes, and 26 references