The Microcomputer Assisted Police Analysis and Deployment System (MAPADS) uses computer-generated maps of crime data for a particular community to chart a unified strategy to combat crime. The 25th district, one of Chicago's biggest and busiest districts, is using the pilot program. The MAPADS crime data are derived from written case reports prepared by field officers and keyed into the computer. Each day, a police officer at the district enters an abstract of each incident report into the system. The software creates a graphic-oriented data base, which is used to prepare maps and more traditional forms of data base reports. Using a spreadsheet-based program, statistical analyses and projections are prepared. Two versions of an incident summary are produced daily. Weekly listings by each of the district's 12 beats are generated, with maps indicating the serious crime occurring on that beat. These are retained by field officers in a notebook. Every 2 weeks, maps and detailed listings are prepared for each beat, instructing field units where to provide concentrated patrol to address patterns in robbery, burglary, and vehicle theft. MAPADS has contributed to a reduction of serious crime in the district and has been instrumental in resolving particular crime problems. Aspects of the hardware and software are described.