Turnaround schools represent a strategy for swiftly revitalizing underperforming educational institutions. This study examined how teachers perceived the role of teacher leadership within one urban turnaround high school. The study addressed the following research questions: 1. How do teachers within an urban turnaround high school conceptualize the role of teacher leadership? 2. In what ways does teacher leadership influence and contribute to the improvement of student performance in turnaround schools? This research was conducted through a concurrent mixed-methods case study that involved one urban turnaround high school. The findings offer valuable insights into teachers' perceptions of teacher leadership and its impact on school improvement initiatives. The results also have implications for refining state policies in Massachusetts concerning turnaround schools, facilitating positive transformations in the roles of teacher leaders within such educational settings. [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.]