Crime maps have only recently begun to emerge as a significant tool in crime and justice. Until a decade ago, few criminal justice agencies had any capability for creating crime maps, and few investigators had the resources or patience to examine the spatial distribution of crime. Today, however, crime mapping is experiencing what might be termed an explosion of interest among both scholars and practitioners. This introduction begins by examining some early examples of mapping of crime, focusing in particular on factors that inhibited the widespread integration of mapping into crime prevention research and practice in the past. It then turns to innovations in mapping technologies and crime prevention theory that have recently brought crime mapping to the center of trends in crime prevention. The final section introduces the contributions that follow and discusses how they illustrate the many uses of mapping in crime prevention. It examines the pitfalls and problems that researchers and practitioners are likely to encounter in developing and analyzing maps, and the potential advances in crime mapping we might expect in coming decades.