Some children with autism have excessive daytime sleep but intervention research for this problem has not been conducted. The present study evaluated procedures with a 13 year old boy who had autism and slept for prolonged periods during the day. Classroom staff at a specialized school implemented procedures with the boy according to an ABAB experimental design. Intervention eliminated daytime sleep through a 6-month follow-up assessment. The study adds to the literature concerning sleep problems in children with autism and extends intervention to excessive daytime sleep. (Contains 1 figure.)