The Hawthorne research concluded that social processes were complex and capable of producing substantial unforeseen effects masquerading as the effects of the actual variables manipulated. The Hawthorne Effect is often considered a problem and not a solution. However, using Hawthorne effects is arguably the most cost-effective crime prevention technique possible. The study reviewed reports that appeared in English, included an initiative with adequate data for coding using the 16-category technique of Clarke and Homel, and included some measure of crime. The 142 pieces of research that met these criteria included crime prevention projects at 211 sites. Fifty-two sites provided information detailed enough to discern anticipatory benefits. Results of the analysis of these cases revealed that 22 displayed prima facie evidence of an anticipatory effect, of which 7 stated reasons or gave enough information to determine the reasons. Possible reasons for anticipatory benefits included the impacts of using moving averages, changes caused by over-recording crime levels in expectation of gaining funds to reduce the crime levels, seasonal effects, regression effects, creeping implementation, preparation-disruption effects, preparation training effects, and publicity/disinformation effects. The analysis concluded that anticipatory benefits of crime prevention programs were not rare and that evaluation studies should contain enough information to allow these effects to reveal themselves. Figures, table, and 51 references