Analytic mapping and geographic databases are increasingly being recognized by police departments as an important tool in crime analysis, crime prevention, and program evaluation. Improvements in technology, reasonably priced computer-based GISs, and the availability of geographic data sources make it possible for law enforcement agencies to use analytic mapping. Police departments using automated mapping systems largely rely on attribute data associated with point locations to produce computer pin maps based on a variety or combination of crime event features. GISs can be used to identify factors contributing to crime and thus allow police to proactively respond to situations before they become problematic. This study of Baltimore County Police use of GIS includes examples that demonstrate the potential of GIS in analyzing crime, developing interdiction strategies, and evaluating the effectiveness of prevention strategies. As this technology gains greater acceptance and is used by more police departments, it will become clear that the ability to produce automated pin maps is only one of many possible applications. Figures, tables, references