The historical review begins with the period prior to 1600 in which formal social control was performed by the military and by citizens organized for mutual defense. Between 1600 and 1867, a centralized police system developed; by 1885, this central system had responsibilities which included crime prevention, the arrest of offenders, and the regulation of public health, factories, and construction and business. After W W II, most of the regulatory functions were removed from the police. The present system is based on prefectural police units which are linked into a national system through the supervision of the National Police Agency. This agency, whose staff has only supervisory functions, is responsible for police education and training programs, procures police equipment, compiles criminal statistics, and furnishes criminal identification services on a nationwide basis. It also coordinates interprefectural police affairs such as the movement of police officers to other prefectures during large-scale mobilizations. Each prefecture is divided into districts, and a police station exercises jurisdiction over each district. The area within each police station is further divided into the jurisdictions of police boxes manned by three officers who maintain close contact with their neighborhoods. While officers may become specialists in various areas, all begin service at police boxes. Entrance into the police is based on a competitive examination; officers are trained at police schools and at a national police college. Officers return to police school for additional training with each rise in rank. Once employed, unmarried policemen live in dormitories, and married officers usually reside in police apartment complexes. In spite of this separation from other citizens, the police have a good relationship with the community. Box officers visit all households twice a year to gather information on residents; and public relations is a major concern of all officers. In addition, neighborhood and business associations work with the police towards crime prevention. A five-item bibliography is included.