Co-teaching, the collaboration between a general education teacher and a special education teacher, is an option that is being perceived by many educators as the means to ensure that special education students have access to the same curriculum as their non-disabled peers as well as the specialized instructional strategies necessary to nurture their learning. While the interest in co-teaching has increased considerably, the presence of two teachers in one classroom presents a supervisory challenge for principals and special education supervisors. Therefore, an investigation of the supervisory roles and practices used among administrators, principals and special education supervisors when evaluating the performance of the special education and general education teachers who co-teach was relevant and timely. A survey entitled Co-Teaching Supervision Protocol Instrument was used to determine the methods administrators, principals and special education supervisors used, when evaluating the performance of the special education and general education teachers who co-teach. The study specifically addressed what supervisors of special education or the highest ranking administrator responsible for special education from the southeast region of the Commonwealth of Pennsylvania said were their administrative responsibilities for supervising co-teaching situations, and whether they believed that these supervisory arrangements were successful in providing guidance to teachers in serving both general education and special education students. Results were based upon data from 51 participants from the targeted population and analyzed using descriptive statistics. About one in four participants used collaboration throughout the process for supervising and evaluating co-teaching, while most did not. Significant discrepancies were found in the importance of tasks associated with the collaborative supervision of co-teachers. Most participants rated the tasks as very important/important, but they did not always include these tasks in the observation process. Two tasks displayed significant disparities in terms of perceived importance and execution of supervisory tasks: the pre-conference and the post-conference meetings with the co-teachers being evaluated. Participants also recognized the supervisory model of the general education administrator supervising both the GET and SET as the most frequently mentioned positive influence on co-teaching evaluation as well as the most frequently mentioned negative reason. Additionally, administrative collaboration, differentiated supervision, and evaluation criteria all were identified skills needing attention for improvement. The results suggested that while an increase in collaborative supervisory arrangements may ensure co-teachers receive more specific and evaluative feedback, school districts must make a commitment to providing policies and structure for conducting co-teaching supervision as well as professional development experiences to support administrators who may use collaborative supervisory arrangements. [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.]