Automated speed enforcement programs were evaluated worldwide to ascertain the effectiveness of such programs at achieving safety benefits. Unlike previous reviews on this topic, a critical review process was used to determine the most likely range of probable safety effects of fixed and mobile automated speed enforcement programs. Among the 90 studies from 16 countries that were initially identified as potential safety evaluation studies, 13 met the criteria for detailed methodological review. On the basis of evidence from the best-controlled evaluation studies, injury crash reductions in the range of 20% to 25% appear to be a reasonable estimate of site-specific safety benefit from conspicuous, fixed-camera, automated speed enforcement programs. No conclusions were reached regarding site-specific effects of mobile enforcement programs. Estimates of systemwide crash reductions likely attributable to covert, mobile speed enforcement programs were based on different subsets of crashes (daytime casualty crashes and daytime speed-related crashes) and were limited to two studies, but also were in the range of 20% to 25%.