Administrators who espouse a commitment to inclusion of students with disabilities in general education classrooms can significantly improve inclusion and co-teaching within their schools. Administrators are instrumental in leading schools to effective inclusion and co-teaching practices (Smith & Leonard, 2005). Those who support inclusion and have a "can-do" attitude have shown a higher ability to successfully implement inclusive practices (Huberman et al., 2012; Marks et al., 2014). Teachers feel that for inclusion and co-teaching to be successful, their school leaders must take an active role in the implementation of inclusion (Isherwood & Barger-Anderson, 2008; Waldron et al., 2011). It may not be enough for administrators to provide professional development to teachers to improve their co-teaching practices. Administrators need professional development themselves on the co-teaching process, collaboration skills, and to learn effective inclusive practices to expand their knowledge base on the co-teaching service delivery option (Mackey, 2014). By learning effective inclusive practices, administrators may be in a better position to support the co-teachers. Nevertheless, even knowing that administrative supports can improve inclusion and co-teaching, supports from administrators remains challenging to implement. The purpose of this case study aimed to explore the impact that professional development for administrators had on their ability to support co-teachers in the inclusive co-taught classroom. Two administrators and two co-teaching dyads participated in this study across two secondary schools outside a large metropolitan city in the Midwest. Administrators engaged in semi-structured, professional development sessions, walk-through observations, and collected evidence from the walk-through observations to complete a data collection form. After each walk-through observation, the administrators provided feedback to the co-teacher dyads which helped to understand the impact the professional development had on their ability to provide feedback to the co-teachers. The co-teachers partook in semi-structured interviews, walk-through observations, and feedback sessions from their administrators to help gauge the effect the feedback from the administrator had on their co-teaching practice. Results showed that professional development trainings on co-teaching and inclusive practices had a positive impact on administrators' ability to provide support co-teachers. Administrators conducted walk-through observations to provide co-teachers with non-evaluative feedback on their co-teaching practices. Evidence showed that by providing co-teachers feedback in tandem was essential to improving co-teaching practices. In addition, the administrators provided positive feedback to the co-teachers that built on the strengths of their current co-teaching practices. This positive feedback revealed that co-teachers felt their confidence improved in their co-teaching practices and validated that they were co-teaching effectively with their co-teaching partner. Findings from this study extend research on co-teaching practices and may have an impact on co-teaching reform. [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.]