Driver gap selection was a principal safety concern at stop-controlled rural intersections. Previous study shows that intersection crashes account for 30 percent of severe crashes and 40 percent crashes happening in rural intersections. Stop sign mounted beacons were installed and evaluated at six selected rural intersections in Iowa. Data were collected before and after installation. The treatments were evaluated by comparing brake activation distance. A two-sample test of means was applied on brake activation distance and logistic regression models were developed to compare driver behavior between before and after installation. The analysis considered differences in driver stopping behavior, including where drivers stop and when they began decelerating in advance of the intersection. Measures of effectiveness focused on unsafe driver behaviors and evaluated how the treatments affected those behaviors. The results provide insights as to the impacts of stop sign mounted beacons on driver behavior.