THE TERMS PRIVATE POLICE, PRIVATE SECURITY FORCES, AND SECURITY PERSONNEL REFER TO THE ARRAY OF PRIVATE INDIVIDUALS AND ORGANIZATIONS THAT SUPPLY ALL TYPES OF SECURITY-RELATED SERVICES, INCLUDING INVESTIGATION, GUARD PATROL, LIE DETECTION, ALARM, AND ARMORED TRANSPORTATION. GENERALLY, PRIVATE SECURITY AUGMENTS POLICE RESOURCES BY FURNISHING SERVICES IN SITUATIONS IN WHICH POLICE CANNOT INTERVENE. ALTHOUGH PRIVATE SECURITY PERSONNEL USUALLY DO NOT HAVE THE SPECIAL POWERS GRANTED THE POLICE, IN SOME JURISDICTIONS PRIVATE POLICE ARE GIVEN EITHER LIMITED OR FULL POWERS VIA AUTHORIZATION, COMMISSION, OR DEPUTIZATION BY A LOCAL OR STATE AGENCY. THE HISTORY OF PRIVATE SECURITY IS LINKED WITH THAT OF THE POLICE. ALTHOUGH SURVEYS CONDUCTED IN THE EARLY 1970'S INDICATE A SATISFACTORY RELATIONSHIP BETWEEN PUBLIC AND PRIVATE POLICE, RELATIVELY LITTLE OPERATIONAL CONTACT BETWEEN THE TWO GROUPS OCCURS. THE 38 STATES WHICH REGULATE PRIVATE SECURITY VARY GREATLY IN THE EXTENT AND CHARACTER OF REGULATION. SPECIFIC PRIVATE SECURITY ROLES INCLUDE PRIVATE GUARDS, PRIVATE DETECTIVES, PRIVATE PATROLMEN, AND PRIVATE ALARM DISPATCH, ARMED ESCORT, ARMORED DELIVERY, AND COURIER SERVICE PERSONNEL. THE RELATIONSHIPS BETWEEN THE EFFECTIVENESS OF PRIVATE SECURITY SERVICES AND SUCH FACTORS AS PERSONNEL SELECTION AND TRAINING ARE LARGELY UNKNOWN. INDICATIONS THAT THE DEMAND FOR PRIVATE SECURITY SERVICES WILL CONTINUE TO RISE ARE NOTED. THE NEED TO FOCUS RESEARCH ON THE ROLE OF PRIVATE AS WELL AS PUBLIC POLICE IS EMPHASIZED. A LIST OF REFERENCES AND A CHAPTER TEST ARE INCLUDED.