Educational leadership and informal teacher leaders are the heartbeat of school initiatives, successes, and growth, and they serve as the foundation of positive school reform. However, it is not known to what extent teacher leaders engage in informal leadership roles or how they use these informal leadership roles to enact change and make positive pedagogical decisions. In turn, educational leaders, teachers, students, and multiple other constituents are affected by this gap in the study of educational leadership. Formal and informal teacher leadership needs to be explored so as to match leadership efforts to the realities of positive reform in schools, especially pedagogically. While our world continues to change profoundly, teacher leadership initiatives remain focused on dated models of teacher leadership that are confounded to formal and traditional leadership positions. In response, this study examines and addresses a gap in the literature -- the analysis of informal teacher leadership -- and further analyzes how this topic has a direct effect on the educational growth of schools. Ultimately, this study will inform educational leadership, allowing educational leaders to see leadership as a shared, collaborative process that requires informal engagement moments that are consistent and part of action plans. [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.]