THE THEORETICAL REVIEW ENCOMPASSES CONCEPTS OF SOCIAL CONTROL, FUNCTIONALISM, CONFLICT, LABELLING, AND EXCHANGE. A SYSTEMS PERSPECTIVE, IN WHICH POLICING IS CAST AS A PARTICULAR FORM OF REGULATION THAT IS NECESSARY IN ALL COMMUNITY SYSTEMS BECAUSE OF A PARTICULAR SET OF PROBLEMS THAT OCCUR BETWEEN PERSONS AND POSITIONS, IS DELINEATED. THE REGULATORY PROCESS IS GOVERNED BY THE LAW OF REGUISITE VARIETY, WHICH ASSERTS THAT THE AMOUNT OF REGULATION A SYSTEM IS CAPABLE OF IS A FUNCTION OF THE NUMBER OF TYPES OF DISTURBANCES DIVIDED BY THE NUMBER OF TYPES OF REGULATORY RESPONSES. A FORMAL MODEL OF REGULATION TAKES INTO ACCOUNT THE POSSIBLE OUTCOMES OF REGULATION, THE DISTURBANCES THAT MAY OBSTRUCT THE DESIRED OUTCOMES, AND THE REGULATORY RESPONSES NECESSARY TO CONTROL DISTURBANCES AND PRODUCE OUTCOMES. THERE ARE AT LEAST FIVE COMMON FORMS OF PLANNED REGULATION IN AMERICAN COMMUNITIES: ANTICIPATORY REGULATION BY PERMISSION, BY PREVENTION, AND BY PUNISHMENT; AND ERROR-CORRECTING REGULATION BY SUBSTITUTION AND BY INTERVENTION. FIVE TYPES OF REGULATORY PROBLEMS EMERGE FROM THE INTERACTION OF PERSONS AND POSITIONS OR FROM THE RELATION AMONG POSITIONS: ALLOCATION; QUALIFICATION; ROLE CONFLICT; INNOVATIONAL CONFLICT; AND ROLE ABUSE. DIFFERENCES AMONG TYPES OF REGULATORY PROBLEMS (TIME SPAN OF THE DISTURBANCE, UNIT OF REGULATION, PREDICTABILITY OF THE DISTURBANCE, UNDERSTANDING OF WAYS TO PREVENT THE DISTURBANCE) LARGELY DETERMINE REGULATORY RESPONSE. WITHIN THIS CONTEXT, POLICING MAY BE VIEWED AS REGULATION BY INTERVENTION IN THE DOMAIN OF PERSON-POSITION INTERACTION. POLICING MAY BE PERFORMED BY A PRIVATE CITIZEN, AN INDIVIDUAL OFFICER, OR A DEPARTMENT, BUT IS CONCERNED ONLY WITH CERTAIN LIMITED PROBLEMS OF ROLE QUALIFICATION AND WITH ROLE INNOVATION AND ROLE ABUSE. THE PROBLEMS WITH WHICH POLICING IS CONCERNED SHARE CERTAIN DIMENSIONS: DISTURBANCES ARE RELATIVELY BRIEF; THE UNIT OF REGULATION IS THE INDIVIDUAL; AND DISTURBANCES HAVE LOW PREDICTABILITY AND ARE NOT WELL UNDERSTOOD. IMPLICATIONS OF THE THEORY ARE SUGGESTED.