The main data sources were a self-report questionnaire administered to 380 juvenile offenders in confinement and information on 135 firearms incidents that led to the arrest of one or more juveniles. Results show that firearms were readily accessible to juvenile offenders and were carried most often for self-defense or aggression rather than as status symbols. Two- thirds of firearms incidents became known to police after calls were made by citizens. These calls often concerned violent or property crimes. One-third of the incidents were detected by the police following searches in public places. Compared to cases initiated by citizens, those initiated by police intervention were more likely to lead to charges being filed and to subsequent adjudication, mainly on weapons charges. This article concludes by recommending that the police increase their monitoring of situations in which juveniles are likely to be carrying firearms illegally. 9 tables and 24 references