In the 21st century, increased school accountability has sharpened the focus of school and district leaders on improving instructional practice to raise student achievement. The implementation of professional leaning communities (PLCs) is one improvement effort in which schools establish collaborative cultures focused on increasing student learning outcomes. Leaders who build learning organizations and implement PLCs in their buildings have the opportunity to create and sustain a context for change and continuous improvement. This study sought to discover how one high school principal sustains a context for continued improvement through PLCs using case study methodology. Schools comprised of PLCs allow educators to grapple with the unique needs of their children in their specific contexts. The problem is that there is limited literature and research to indicate how leaders sustain PLCs over time. The knowledge of how to sustain learning and improvement over time is needed to facilitate leaders in moving their schools into cultures of collaboration, which is a marked difference from the past 200 years. Therefore, the overarching research question of this study was: How do administrators, teachers, and PLC leaders in a school that has developed and implemented PLCs, sustain a context for continuous improvement? Using a 360-degree analysis of the case study school, three major findings emerged from this study: the PLCs in a learning organization operate at various phases of PLC development, making the change process to develop, implement, and sustain the work of continuous improvement through PLCs fluid, dynamic, and complex; there are 10 strategies for sustaining the work of PLCs that contribute to the success of effective and mature PLCs to sustain continuous improvement and are therefore instructive in nature; and, the work in the Developing and Implementing phases is critical to the success of PLCs and their ability to sustain a context of continuous improvement. [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/en-US/products/dissertations/individuals.shtml.]