This study explores the learning theories communities of practice (Lave & Wenger, 1991) and transformative learning theory (Mezirow, 1978) in the context of mentor teaching. The landscape of teacher education preparation programs is shifting its focus to practice-based teacher education, with the inclusion of high-leverage teaching practices. This study delves into four mentor teachers' experiences. Through a case study approach, this work examines how a change in teacher education programs impacts the mentor teachers' experience. The learning theories, communities of practice, and transformative learning, were used as the lens with which to analyze the data. Monthly surveys, individual interviews, and a group interview were used as data instruments. The data demonstrated ways in which mentoring is a disorientating experience, as well as ways in which communities of practice and transformative learning work together to foster a transformative experience for mentor teachers. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]