This study was prompted by the continuous rise in expectations for students with disabilities to have access to the general education curriculum within the general education classroom. This study was a program evaluation on the Marilyn Friend co-teaching models that utilized Stufflebeam's (1960) Context, Input, Process, Product (CIPP) program cycle at three middle schools in one upstate South Carolina school district (Social Science Space, 2017). Data were collected via teacher surveys and follow-up interviews with general education and special education teachers, middle school administrators, and appropriate district office personnel. The survey population included 31 middle school general education and special education teachers. The survey consisted of 11 questions: four multiple-choice, one Likert scale question, one check all that apply question, and five open-ended questions that addressed co-teaching training, planning, professional development, and the overall implementation of the Marilyn Friend co-teaching models. Follow-up interviews with five middle school administrators, one director of special education, and 19 general education and special education teachers helped to complete the program evaluation. Their perceptions of the Marilyn Friend co-teaching models revealed that teachers found co-teaching was beneficial for all students, but additional time was needed for planning purposes with their co-teachers. This study was grounded in Bandura's (1994) self-efficacy theory. Findings from the survey and the interviews brought about common themes centered around the overall implementation and sustainability of the co-teaching program. The co-teaching program needs some improvements in regard to the initial training offered, professional development/coaching throughout implementation, scheduling, and co-planning to make the program most effective. [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.]