Crime analysis is defined as a rational system of data analysis for enhancing and validating decisionmaking in crime reduction efforts. Precinct crime analysis consists of three distinct steps: summarizing and extracting information relevant to the precinct's crime situation, arriving at a particular decision based on the statistical data supplied, and evaluating the effectiveness of the decision. The section on organizing a data system aids precinct personnel in establishing mandated minimal baseline procedures and presents more refined procedures beyond the mandated minimum. Such techniques usually concentrate on being able to identify various common pieces of information about groups of incidents (e.g., the location, the time, and the physical description of the perpetrator). This pattern recognition involves identifying similarities among incident and arrest data and identifying clusters of similar items. The tools used to accomplish these identifications fall into three categories; chronologies, and cross-tabulation tables. A schematic diagram of the precinct crime analysis process is then presented. The concluding section outlines a general approach for evaluating the effectiveness of the response. A specific example from the 41st precinct demonstrates one concrete possibility of ongoing effectiveness monitoring. The manual includes numerous charts, graphs, and illustrated procedures.