A list of almost 200 organizations was compiled from several reference sources, a wide variety of youth-serving organizational literature, and from 'Congressional Record' listings of official Juvenile Justice and Delinquency Prevention Act supporters. Each organization was then contacted by letter and followup telephone conversations to determine the extent of involvement and interest; consequently, 103 national nongovernmental organizatons meeting the research criteria were identified. The types of national nongovernmental organizations found were youth membership organizations, adult organizations directly involved with the juvenile justice system, adult organizations indirectly involved with the juvenile justice system, and Juvenile Justice and Delinquency Prevention Act supporters uninvolved with the juvenile justice system. The involvement of each of the 103 national nongovernmental organizations consists primarily of participating in national youth-serving collaborations; sponsoring Federal, State, and local advocacy efforts; creating and operating direct service programs for predelinquent and delinquent youth as well as training and information forums for juvenile justice practitioners; and providing a wide variety of juvenile justice resources for organizaiton members and the public at-large. Only 31 of the organizations were involved with serious and violent juvenile offenders. Twenty-four of these organizations receive partial or total financial assistance from government agency. Only seven organizations operate serious and violent juvenile offender endeavors exclusively with private funds. The study's overall conclusion is that the vast majority of national nongovernmental juvenile justice and serious and violent juvenile offender endeavors have been sponsored by public and private partnerships. This suggests that any major contraction of Federal, State, and public support would hinder future national nongovernmental involvement with the juvenile justice system as well as serious and violent juvenile offenders. About 270 bibliographic listings are provided.