Throughout the years, special education has changed and evolved to best meet the needs of students on IEPs and with diverse learning needs. Teachers are put at the forefront to help students be successful in the 21st century. One way to meet the various learning needs of students, schools have incorporated the co-teaching model. The co-teaching model involves two teachers, a special education teacher and a general education teacher. Co-teaching requires co-teachers to not only co-teach, but co-plan and co-assess. A strong relationship is a significant factor in successful co-teaching. In this study, ELA and math teachers at a middle school were provided with a month-long professional development series. The professional development included direct instruction the most collaborative co-teaching models, including alternative teaching, parallel teaching, station teaching, and team teaching. The series was virtual and recorded, for teachers to watch on their own time, and throughout the month, implement the models. Teachers also took an online pre- and post-survey with questions surrounding their efficacy and comfortability around co-planning and co-teaching specific to the co-teaching models learned and included in the PD. By the end of the study, there was significant growth in the teacher's comfortability and efficacy in implementing a variety of the co-teaching models presented in the PD. [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.]