This single-subject multiple-baseline across participants study was designed to investigate the effects of explicit instruction with manipulatives on the conceptual and procedural knowledge of addition and subtraction of like and unlike fractions of elementary school students with autism. This study included six 8- to 12-year-old students with mild to moderate autism who demonstrated math difficulties. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]