This fifth edition updates previous editions and is based on questionnaires completed in 1984 by more than 300 criminal justice agencies. Questionnaires were mailed to all the agencies listed in the 1981 edition as well as to additional agencies identified by National Criminal Justice Reference Service staff. The following criteria guide the selection process: the organization's service area is national or regional in scope; the information provided is a major component of the agency's function; information services include data base searches, document dissemination or delivery, practical information on setting up programs, reference services, and technical assistance; the organization answers telephone and mail requests and does not require users to visit the facility to obtain information; and costs for services or membership are not prohibitive or excessively restrictive. Information presented for each organization includes parent organization/sponsoring agency, information center/library, address, telephone number(s), user restrictions, year established, head of center, number of staff, contact person, objectives, services offered, collection size, and publications. Appendixes provide listings of members of the Criminal Justice Information Exchange of the Criminal Justice Information Exchange group and their addresses, State criminal justice systems representatives, and Federal Information Centers and telephone numbers, as well as organization charts of the U.S. Department of Justice and the National Institute of Justice.