The National Crime Information Center (NCIC) is a computerized index of missing persons and criminal information and is designed for the rapid exchange of information between criminal justice agencies. Users access the NCIC computer located at FBI headquarters through regional or State computer systems or with direct tie-ins to the NCIC computer. The data is stored in 12 files: article, boat, Canadian warrant, gun, interstate identification index, license plate, missing person, securities, U.S. Secret Service Protective, unidentified person, vehicle, and wanted person. The booklet's instructions cover the importance of accurate information, the identifiers required to make an inquiry of the files, the nature and use of each file, and procedures for off-line searches. Case examples illustrating the use of the system and a form for ordering other NCIC publications are included.