This study which compared lighted and unlighted intersections on the basis of accident experience, considered 7 measures: night accidents per year, day accidents per year, total accidents per year, ratio of night accidents to total accidents per year, night accident rate, day accident rate, and total accident rate. Data collection techniques and the analysis of results are outlined. The study found that night accidents are significantly reduced at rural at-grade intersections when illumination is installed; the magnitude of reduction varies with the dependent variable that measures accident experience. The night accident rate and the night accident/total accident ratio are significant measures of accident experience when the influence of illumination on night accidents is considered. Illumination results in a 45 percent reduction in the night accident rate and a 22 percent reduction in the night accident/total accident ratio. Comments are made on other safety improvements of rural at-grade intersections.