The police caution requires that information about individual offenders, offenses, responses, and outcomes be monitored. If such information is collected regularly, it should be possible to answer questions dealing with the rate of cautioning as a proportion of all juveniles coming to police notice, who is cautioned, whether cautions are increasing at the expense of prosecutions, whether local policies encourage police to make wider use of cautioning, how court decisions are affected, and whether the overall rate of reported crime is affected by a policy of diversion. Guidelines for collating, presenting, and using information are outlined, and the role of management committees and computers in data analysis is discussed. Supplemental information on indictable offenses and information collection forms are appended. References, tables, and illustrations.