Synchronous schedules of reinforcement align the onset and offset of the response with the onset and offset of the reinforcer. In this study, we used a multiple-baseline-across-classes and reversal design to determine the effects of a synchronous reinforcement schedule, arranged as an interdependent group contingency, on time spent following rules and disruptive classroom behavior during independent work periods in three elementary classes: two first-grade classes and one fourth-grade class. Additionally, we compared the effects of a synchronous reinforcement schedule with those of a continuous noncontingent schedule in the fourth-grade class. The synchronous schedule increased students' time spent following rules and decreased disruptive classroom behavior across all classes. Furthermore, noncontingent delivery of those stimuli did not produce changes in behavior relative to baseline. Students in the two first-grade classes reported preferring the synchronous reinforcement condition to baseline. Students in the fourth-grade class reported preferring the noncontingent access condition.