The present study sought to evaluate the efficacy of an interdependent group contingency program on increasing homework completion and accuracy rates in fourth grade students in an elementary school. In addition, the present study attempted to determine whether randomized reinforcement was more effective than constant reinforcement. Overall, the data suggest that interdependent group contingencies using both constant and varied reinforcement were effective in improving both homework completion and accuracy. Although the homework completion rate for the control class remained relatively consistent across the measurement period, rates for both treatment classes increased with use of both varied and constant reinforcement. However, in contrast with most previous research, constant reinforcement appeared to be more efficacious than varied reinforcement. (Contains 2 figures.)