Urban school districts' educational leaders face what seem to be an endless number of challenges, such as closing the achievement gap, enhancing student performance, building teacher capacity, creating leadership opportunities, and adapting to a student population that is changing rapidly and increasingly made up of students from low socioeconomic status backgrounds who are limited English speakers and/or English language learners. Through the lens of complexity theory, this three-year instrumental case study examined the leadership practices of two Lynch Leadership Academy Principal Fellows in relation to their leadership growth project that they determined would benefit from improvement and, as a result, would be implemented in their urban schools. Using principal and teachers' interviews and observation fieldnotes of the professional learning communities meetings at the schools, this study chronicled the actions and behaviors of the principals and teachers through their interdependent and mutual relationships as they developed a theory of action and conducted their Leadership Growth Project, taking into account the concepts of complexity theory and the influence on the school community. The findings demonstrate that principals, through their leadership and relationships with their teachers and their engagement in professional learning community activities, complicated and disrupted the complacency, compliance, and comfort of the teachers. The formation of a theory of action, however, which was a way for the teachers and the principals to satisfy the needs of their urban school community in response to the challenges they faced, was sparked by such disruptions. Additionally, teachers had to reconsider how they interacted with their students as a result of their capacity for self-organization at the edge of chaos. A conclusion of this research is that in order to achieve successful professional learning outcomes and emergence through adapted change that incorporate the principal's leadership, teachers must be willing to communicate practice-related issues and to offer and accept constructive criticism in an environment of disequilibrium. [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.]