Pedestrian countdown signals installed at five intersections in Montgomery County, Maryland, were evaluated with a before-and-after study. The effect of the countdown signals on pedestrian and motorist behavior was determined by observing the signal indication when pedestrians entered the intersection, the number of pedestrians remaining in the intersection at the release of conflicting traffic, conflicts between pedestrians and motor vehicles, and vehicle approach speeds to the intersections. On the basis of the observational study, the pedestrian countdown signals did not have a negative effect on pedestrian behavior. The vehicle speed observations found that pedestrian countdown signals had no effect on vehicle approach speeds during the pedestrian clearance interval (i.e., flashing "Don't Walk" indication). Pedestrian behavior observations found that although 2 of the 20 crosswalks experienced a statistically significant decrease in the number of pedestrians who entered on "Walk," 6 crosswalks experienced a significant increase. Additionally, none of the intersections had a significant increase in the number of phases with pedestrians remaining in the intersection at the release of conflicting traffic. The observational study of conflicts found a significant decrease in pedestrian-motor vehicle conflicts after the installation of the pedestrian countdown signals at four of the intersections at which conflicts were observed. A survey of pedestrians was also conducted. Results of the survey indicated that, generally, pedestrians are aware of the countdown signal and understand the countdown indication.