GIS are a type of computer technology gaining increasing acceptance in law enforcement. These information systems allow users to make connections between seemingly unrelated bits of information gathered over time and over large and diversified geographical areas. Such capabilities have the potential for significantly improving the effectiveness of criminal investigations, as well as crime prediction and crime prevention efforts. GIS can be used for theoretical research. They can also map burglary opportunities by describing areas according to whether they are residential or nonresidential, the density of single individual households, double-individual two-income households, relative time away from home, and household activity rates. Other possible uses relate to drug crackdowns, environmental planning for crime prevention, and helping police understand crime placement and displacement. The police department of Long Beach, Calif. exemplifies the use of GIS to use limited resources more efficiently by deploying police in areas most likely to produce arrests. The costs of these systems pose a barrier to their use and can be overcome by piggybacking them on existing computer systems or creating or joining a regional GIS network. 42 references