Teacher leaders are those who have strong pedagogical skill sets, demonstrate the capacity to impact their colleagues' practices, and have the ability to influence and facilitate improvements in teaching and learning inside and outside of their schools. When teacher leaders provide professional development to improve teaching practices (i.e. pedagogical content knowledge), this networking opportunity allows teachers to collegially interact with colleagues who are willing to collaborate and share their knowledge. The purpose of this study was to examine how the experienced secondary teachers -- Master Teacher Fellows (MTFs) -- underwent changes in their professional identity as they facilitated PDs for K-12 teachers in their districts. The data obtained from individual pre and post-interviews with the MTFs and archival data from the leadership program that the MTFs participated in were analyzed using multiple coding methods. The findings suggest that practicing and reflecting on teacher leadership in the context of teacher-driven professional development can cultivate changes in the professional identity of teacher leaders; therefore, such opportunities could be an integral part of teacher leadership development programs and candidates should be encouraged and supported by those programs.