Research Summary: We report on the findings of an updated systematic review and meta-analysis of the effects of closed-circuit television (CCTV) surveillance cameras on crime. The findings show that CCTV is associated with a significant and modest decrease in crime. The largest and most consistent effects of CCTV were observed in car parks. The results of the analysis also demonstrated evidence of significant crime reductions within other settings, particularly residential areas. CCTV schemes incorporating activemonitoring generated larger effect sizes than did passive systems. Schemes deploying multiple interventions alongside CCTV generated larger effect sizes than did schemes deploying single or no other interventions alongside CCTV. Policy Implications: The results of this systematic review—based on 40 years of evaluation research—lend support for the continued use of CCTV to prevent crime as well as reveal a greater understanding of some of the key mechanisms of effective use. Of particular salience is the continued need for CCTV to be narrowly targeted on vehicle crimes and property crime and not be deployed as a “stand-alone” crime prevention measure. As CCTV surveillance continues to expand its reach in both public and private space and evolve with new technology, policy will benefit from high-quality evaluations of outcomes and implementation.