Transit service reliability is an important determinant of the level of serviceexperienced by passengers. Bus drivers play a key role in translating a schedule to an actual service and, as a result, could influence the resulting reliability. Therefore, understanding drivers’ behaviors is useful for a variety of purposes such as designing bus schedules and developing real-time operations control strategies. In Transit Lab, the effects of bus drivers’ reactions to schedules, given the status of the buses they are operating, on service reliability are investigated and quantified analytically and empirically. The hypothesis that drivers may deliberately, as a form of control, lengthen or shorten dwell times at stops or adjust speeds between consecutive stops depending on whether buses are ahead or behind schedule is examined. Relationships such as the progression of reliability from stop to stop as a function of drivers' possible reactions to the schedule are explored in an empirical study using a large Automatic Vehicle Location (AVL) data set collected by The Ohio State University’s Campus Transit Lab (CTL). The drivers’ reactions to the schedule are found to be helpful in improving service reliability.