A single‐subject ABA reversal design was applied to evaluate the effectiveness of a limited 8‐s safety belt reminder system and two modified reminder systems (a delayed and second reminder) to increase the safety belt use of 13 drivers. The research was conducted with a specially equipped research vehicle that permitted the manipulation of different safety belt reminder stimuli and the unobtrusive recording of a driver's belt use. For 2 subjects, the limited 8‐s reminder increased safety belt use. For another 2 subjects, the second reminder markedly increased belt use. Some subjects were uninfluenced by the reminder systems presented; others always buckled up during both baseline and intervention conditions. The approach and results are discussed with regard to the application of behavior analysis methodologies (e.g., cumulative records) and principles (e.g., schedules of reinforcement) to advance the utility and investigation of safety belt reminder sy