The purpose of this study was to describe how the school and classroom cultures affected practices of inclusion for students with disabilities and how the inclusionary practice of co-teaching was influenced by the school culture. This study sought to investigate school and classroom cultures and their impact on practices of inclusion. It also addressed the perceptions of the impact that the school and classroom cultures had on co-teaching and why some practices are effective or not effective for co-planning or co-implementation. A multicase study design was used to gather and explore observations and interviews. Data were analyzed through qualitative methods with a focus on norms, values, and routines. This study provided an understanding of how school and classroom cultures affected inclusion within one school district in Virginia in order to inform elements needed for successful inclusion of students with disabilities through use of the co-teaching model. [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.]