Limited co-planning between special education and general education co-teaching partners has been documented in professional literature as a significant problem. Special education teachers do not adequately co-plan for the implementation of accommodations for students with disabilities educated in the general education classroom. The purpose of this study was to collect and analyze the perceptions of special education teachers in one suburban elementary school district in the United States regarding co-planning with regular education teachers. The theory of self-efficacy was utilized as the conceptual framework to understand how teachers' beliefs and experiences influenced planning and goal setting for special education students. Research questions were designed to capture the perceptions of elementary school special education teachers by documenting their roles, beliefs, and self-efficacy for co-planning. In this qualitative case study, 8 elementary school special education teachers currently holding co-teaching assignments in a public school district were interviewed. Interview data were analyzed using thematic analysis. School documents were also analyzed as a method of triangulation. Results were reflective of the theoretical framework in that special education teachers' believed that their co-planning experience influenced their general teaching efficacy, but not their personal teaching efficacy. They felt more prepared to teach general education students, but maintained their personal expertise in teaching special education students. The implications for social change include enhanced morale for teaching in inclusive classrooms for special education teachers, enhanced social interaction between co-teachers and students, and enhanced learning for all students including those with disabilities that might result in opportunities for educational and career advancement. [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.]