The purpose of this study is to address teacher retention within a small independent school. Nationally teacher turnover is at a critical level, and few schools are exempt from this crisis. As in many small independent schools, resources are limited. Any changes need to be impactful and sustainable, and exploration of the reasons behind the consistent level of turnover is necessary to continuity of program. This 3-month mixed methods study used improvement science in two consecutive Plan-Do-Study-Act cycles to support the retention of teachers within their first 5 years of teaching at the school by addressing the instructional practice of co-teaching. The first cycle focused on the co-design of professional learning by a small group of teachers and an administrator. The second centered on the piloting of the professional learning experience. Methodology included pre- and post-intervention surveys and semi-structured interviews with teachers. Data provided insight into the impact of the teacher leadership experience, the development of co-teaching relationships, and the aim of retention. Teachers' involvement in the professional development was identified as an opportunity for teacher influence but did not substantially change teachers' perception of themselves as teacher leaders. The intervention itself has the potential to improve co-teaching relationships, communication, and parity when teachers are open to this change. Ultimately, teachers expressed a high level of intent to return because they felt connected to colleagues beyond their co-teaching relationship and because the administration was aware and engaging teachers on problems central to the school's pedagogy. [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.]