The passing of the Education for All Handicapped Children Act---later renamed the Individuals With Disabilities Education Act---mandated that schools and districts ensure that all available education services were comparable between students with disabilities and general education students. This mandate led to students with disabilities and general education students being placed in the same setting and requiring students with educational disabilities to participate in taking the same assessments as their nondisabled peers in these classrooms. The Individuals with Disabilities Education Improvement Act, aligned with the No Child Left Behind Act, emphasized improved student academic outcomes. Even with the initiation of Every Student Succeed Act, this goal is still the same. To meet the needs of students with disabilities, many schools have implemented a co-teaching model with the idea of successfully serving the needs of a varied student population. The purpose of this research was to investigate if there is a difference in end-of-course (EOC) scores for students with disabilities taught in a co-teaching setting in comparison to students with disabilities who are taught in a traditional setting in an Algebra I course. This study compared mathematics EOC scores between co-teaching and traditional mathematics classes to determine whether receiving instruction in an inclusion setting increases student achievement on EOC assessments. A nonexperimental, quantitative research design was used. Individual student data from co-teaching Algebra I classes and student data from traditional Algebra I classes of one high school were compared using EOC archival data for school years ending 2013, 2014, and 2015. This research provides guidance for placing students with educational disabilities into co-teaching environments to increase academic proficiency on high-stakes assessments. There were no statistically significant differences between the two settings, but findings from the research showed there were numerical differences. [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.]