THERE IS NO STATUTORY DEFINITION OF A 'CAUTION,' ALTHOUGH THE PRACTICE OF CAUTIONING HAS A MEASURE OF STATUTORY RECOGNITION. A CAUTION IS A FORMAL ACT, DISTINCT FROM VARIOUS KINDS OF GUIDANCE AND INFORMAL WARNINGS WHICH POLICE OFFICERS GIVE TO THE PUBLIC. IT REPRESENTS AN INTERMEDIATE STEP BETWEEN TAKING NO ACTION WITH RESPECT TO AN OFFENSE AND DECIDING TO PROSECUTE. IT IS AN INTEGRAL PART OF THE SYSTEM FOR DEALING WITH JUVENILES AND IS SOMETIMES USED FOR ADULTS. THERE ARE IMPORTANT DIFFERENCES IN THE CAUTIONING OF JUVENILES AND OF ADULTS AND ALSO A SEPARATE SYSTEM OF ISSUING WARNINGS TO MOTORISTS AND TO PROSTITUTES. DURING THE PERIOD 1958 THROUGH 1977, JUVENILES WERE MOST FREQUENTLY CAUTIONED FOR THEFT, HANDLING STOLEN GOODS, SEXUAL OFFENSES, FRAUD, AND FORGERY. THERE ARE CONSIDERABLE VARIATIONS IN CAUTIONING RATES BETWEEN POLICE FORCE AREAS. THE METROPOLITAN POLICE, FOR EXAMPLE, RARELY CAUTIONS ANY MALE OVER THE AGE OF 17. NONE OF THE EXISTING STUDIES HAS IDENTIFIED EXTRINSIC FACTORS TO ACCOUNT FOR THESE VARIATIONS. CRITERIA FOR DECIDING TO CAUTION INCLUDE THE CIRCUMSTANCES OF THE OFFENDER, THE OFFENSE, THE ATTITUDE OF THE VICTIM, AND THE TREATMENT OF CO-OFFENDERS. IT IS SUGGESTED THAT THE IMPLICATIONS OF THIS NECESSARY PRACTICE SHOULD BE CONSIDERED BY THE HOME OFFICE. FOOTNOTES AND APPENDIXES ARE INCLUDED IN THE MEMORANDUM. (LWM)