The No Child Left Behind Act (NCLB) of 2001 is based on the principle that setting high academic expectations and establishing measurable goals can improve individual outcomes in education. Under NCLB, states are required to develop assessments in basic skills to be given to all students in certain grades if those states are to receive federal funding for schools. The purpose of this study was to determine if reduced inclusion class sizes affect student's scores on the Assessment of Skills and Knowledge (ASK) test administered in one northeastern US state and to solicit teachers' opinions of smaller class sizes. Inclusions classes are those that enroll special needs students. Theoretical foundations guiding this study included social learning theory, constructivist theory, and the cooperative learning theory. The key question this study focused on was whether or not smaller class size has an effect on academic achievement for special needs inclusion students. Using archival data, this ex post facto study found a statistically significant difference using a MANOVA, F(2,34) = 14.55, p less than 0.0001 for the research question investigating the effect class size has on special needs inclusion students. Positive social change implications include helping inform the efforts of local, state, and federal education officials to narrow the achievement gap between regular and special education students. These results could provide justification to school boards for hiring more staff, creating and passing building addition referendums, and providing professional development to identify ways to adjust school schedules and reduce class size. [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.]