Detectives are said to 'make' crime in that their investigations lead them to conclude whether or not a specific event constituted a crime. The text focuses on understanding detectives' discretion in constructing cases and their outcomes. The sample consisted of 295 cases that came to the attention of detective teams during the study period. Occurrence reports, investigative interviews, suspects, and field notes were all sources of data. The cases of 56 persons eventually accused were then followed via interviews, court observation, and transcripts to the point of disposition. The picture of detective work that emerges is one of relative autonomy and low visibility. However, the study found detective work to be reactive rather than proactive, since the control of cases is initially in other hands; e.g., complainants' and patrol officers'. Once detectives take cases they are very much in control. They exercise discretion through their choice of what investigations to undertake, what questions to ask, and how to interpret the answers. Discretion is also involved in writing accounts; dealing with complainants, suspects, and accused persons; and predicting the outcomes of cases. Organizational rules are only a framework within which detectives exercise discretion. Appendixes contain a response to the study from the jurisdiction studied and the author's reply. About 250 references and an index are provided.