A growing body of work has emerged regarding the responsibilities required of district leaders in establishing plans that initiate and create conditions for sustainability of continuous improvement achieved through a systemic reform structure such as professional learning communities. However, limited research exists in respect to sustaining cultures of continuous improvement in rapid growth districts. Rapid growth districts can be described as school systems, which construct and open multiple campuses annually. The underlying premise of this study considered how humans interact with one another within a rapidly changing professional organization. Change theory, professional capital, organizational learning theory, and system reform emerge as the conceptual framework in this study of district support of professional learning communities. Data collection for this qualitative descriptive case study included interviewing six K-12 principals, administering the PLCA-DS survey to 247 K-12 staff members, and document review. Recognition of the importance of the PLC framework, building capacity, development of collaborative culture, and issues resulting from constant change due to rapid growth were the four themes generated by the participants to support continuous improvement in a rapid growth district. The four themes combined with the components of the conceptual framework outline how district leaders in a rapidly changing environment cultivate a process leading to system-wide 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.]