This report summarizes the results of an evaluation ofpublic surveillance systems in Baltimore, Chicago, and Washington, D.C., examining how systems in each of these jurisdictions were selected and implemented and assessing the degree to which they achieved their intended crime prevention impact. The study also explored whether surveillance cameras displaced crime or yielded a diffusion of benefits to areas just beyond the cameras reach, and included a cost-benefit analysis component in two of the three study sites. Findings indicate that in places where cameras were sufficiently concentrated and routinely monitored by trained staff, the impact on crime was significant and cost-beneficial, with no evidence of crime displacement.