Older drivers represent the second highest injury and fatality rate, next to younger drivers, per 10,000 licensed drivers. They are also first in fatalities per 100 million miles driven. The disproportionate fatality risk is linked to several known factors ranging from failure to yield, cognitive and visual limitations, seat belt use abstention, and fragility. Previous research has used a smartphone app to provide feedback to teen drivers regarding risky driving behaviors. Its modified, universally designed version, RoadCoach, has been proposed as an assistive tool to reduce risky driving behaviors among older drivers. The app was found to have high usability through a series of focus groups, usability tests, and controlled field test among older drivers. The safety features of the app aimed to reduce risky behaviors, e.g., warnings for hard braking/turning, advanced curve notifications, and speeding, had high user acceptance. This study is focusing on a field operational test (FOT) with 30 older drivers across Minnesota and Kansas using the RoadCoach prototype. The FOT examines older drivers' baseline driving behavior (3 weeks), driving behavior with RoadCoach feedback (6 weeks), and a follow up baseline period (3 weeks). The outcome of the study will be to determine if the RoadCoach app can successfully reduce speeding, hard braking, and excessive acceleration (lateral and longitudinal) among older drivers and determine if changes in behavior persist after the treatment is removed. A successful deployment of the app among older drivers may provide a tool to help prolong safe, independent driving among our nation's seniors.