The Effect of Moonlight on Outdoor Nighttime Crime

23 Pages Posted: 8 May 2019

Date Written: April 9, 2019


The use of outdoor lighting, particularly through street lights, is a common tool for policy makers attempting to reduce crime. Research on the effect of lights on crime, however, are limited as installing or improving street lighting may affect the community in ways beyond merely increasing outdoor lighting. Welsh and Farrington’s (2008) study suggested that improving street lighting may also improve informal social control in the area as it reflects improved street usage and investments in the community. This paper uses moonlight as a unique measure of outdoor ambient lighting that avoids the issue of community cohesion and examines the effect of lighting directly. The amount of actual moonlight a city receives each night is measured using the interaction between the percent of the moon illuminated and the proportion of the night without clouds. This interaction creates significant variation in moonlight between cities and across nights in the same city. Contrary to past research on lighting, this study finds that brighter nights, those with a full moon and no clouds, have significantly more crime than nights without any moonlight. These results suggest that there are heterogeneous effects of outdoor lighting by dosage and that more research on possible criminogenic effects of low dosages of outdoor lights are needed.

Keywords: CPTED, crime prevention, school crime

Suggested Citation

Kaplan, Jacob, The Effect of Moonlight on Outdoor Nighttime Crime (April 9, 2019). Available at SSRN: or

Jacob Kaplan (Contact Author)

Princeton University ( email )

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