The surviving archives of the English and Welsh police forces, which remain in police hands, are an invaluable means of illuminating not only the police themselves but also the realities of law enforcement on the streets, perceptions of the law, and a variety of much broader aspects of social history. This paper provides an introduction to these sources, the problems in their use, and an outline of the kinds of things they contain. The documentation that survives in the archives takes a variety of forms: written, printed, photographic, and cinematic. It begins in the middle of the 19th century after police forces became obligatory for local government by the County and Borough Police Act of 1856, but it remains incomplete, since documentation has survived largely by accident rather than design. It covers law enforcement by the police, ranging from chief constables' letterbooks and force orders to the chargebooks of police stations and the journals of individual constables. The archives generally focus on the day-to-day issues of regulation and petty offenses. The police personnel registers provide probably the best record of the physical characteristics of working-class males for the late 19th and early 20th centuries. These men were exceptional in that they met the physical requirements of the police and that they volunteered for the police. The registers also provide information on what men did before they joined the police and, in some cases, after they left the police force. The discipline books and other material in police archives might be used to obtain a glimpse of the working- class family, as well as of attitudes to the law and to the police. 23 notes