This study investigates the impact of principal turnover on teacher leadership, using mixed methods to analyze teacher leadership in low and high principal turnover elementary schools. Data collection includes teacher surveys and interviews with principals in four low turnover and four high turnover schools. Quantitative results indicate significant differences in teacher leadership, while qualitative findings reveal themes such as teacher professional development, support, leadership opportunities, anxiety, and sustainability. Mixed methods results suggest the need for increased time to develop trust between principals and teachers, greater teacher involvement in school leadership, more opportunities for teachers to share leadership, and a better balance between work and personal life. Implications highlight the need to enhance teacher leadership capacity, facilitate the transition from delegation to distributed leadership, provide support for teachers and principals, and implement effective principal succession planning. [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.]