Over 35 years of behavioral research have shown contingency management systems in the classroom are highly effective for treating children with behavior problems. Questions remain if such systems can be enhanced by the functional assessment process. This case study looks at a nine-year-old child with oppositional behavior who was on a contingency management program. After a thorough functional assessment the author determined that poor sleep patterns contributed to poor performance on the token system the following morning. This post-hoc analysis of the data conformed to a reversal design. The program showed a functional relationship between neutralizing sleep difficulty and increasing of point earned and the decreasing of episodes of response cost. (Contains 3 figures and 1 footnote.)