Students identified as students with disabilities receiving special education services continue to perform below their same grade level peers in mathematics. Since the inception of the Individuals with Disability Act and the subsequent Every Student Succeeds Act, the United States has been shifting to a more inclusive education for all students. However, despite more students being educated within the general education settings, a gap still exists in standardized testing scores. The purpose of this study was to investigate if professional development on co-teaching practices and the use of a planning template to execute those practices could lead to higher achievement for students with disabilities in the area of mathematics. The study utilized the NWEA MAP assessment to analyze students with disabilities that were in a fifth-grade co-taught classroom RIT scores in the Fall of 2021 compared to the Winter of 2022 to determine if students with disabilities demonstrated at least a 12-point gain. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]