The police procedural is a subgenre of detective fiction which attempts to convincingly depict the activities of a police force as they investigate crimes. While traditional detective novels usually concentrate on a single crime, police procedurals frequently depict investigations into several unrelated crimes in a single story. While traditional mysteries usually adhere to the convention of having the criminal's identity concealed until the climax (the so-called whodunit), in police procedurals, the perpetrator's identity is often known to the audience from the outset. Police procedurals depict a number of police-related topics such as forensics, autopsies, the gathering of evidence, the use of search warrants and interrogation.

There were earlier precedents, but Lawrence Treat's 1945 novel V as in Victim is often cited as perhaps the first "true" police procedural. Another early example is Hillary Waugh's Last Seen Wearing ..., 1952. Even earlier examples, predating Treat, include the novels Harness Bull, 1937, and Homicide, 1937, by former Southern California police officer Leslie T. White, P.C. Richardson's First Case, 1933, by Sir Basil Thomson, former Assistant Commissioner of Scotland Yard, and the short story collection Policeman's Lot, 1933, by former Buckinghamshire High Sheriff and Justice of the Peace Henry Wade.