This guidebook is about the computerized mapping of crime locations. The guidebook's fundamental objective is to provide public housing authorities (PHAs), local police departments (PDs), and criminal justice researchers with a straightforward, relatively inexpensive method for measuring crime in public housing developments and other multifamily housing complexes (see Glossary for definitions of bold faced words). The approach presented here was the focus of recent research sponsored by the U.S. Department of Housing and Urban Development's (HUD) Office of Policy Development and Research (PD&R). That research project is part of PD&R's ongoing criminal justice research agenda, aimed at creating "tools" to facilitate the evaluation of crime prevention programs at the individual housing development level. The widespread commercial availability of easy-to-use geographic information systems (GIS) and the subsequent embracing of GIS by PDs as an important crime analysis tool were crucial in laying the groundwork for the approach presented here.