Purpose and Method of Study: The primary purpose of this study was to understand the lived experiences of principals of high schools in Oklahoma. The secondary purpose of this study was to use the lived experiences to make recommendations toward enhancing principal sustainability. This qualitative study used phenomenological research to understand the challenges, difficulties, and recommendations for improvement from principals of larger high schools in Oklahoma. In-depth interviews were used to collect data. Those interviews were taped, transcribed, and sent back to the principals for review. Following Creswell's (2013) data analysis method, themes emerged that were later used to develop 1the phenomenon. Findings and Conclusions: The difficulties and challenges that principals faced centered around personnel issues, time responsibilities, high-stakes accountability measures, and the behavioral characteristics of some students that were challenges. This study also identified factors that could play an important role in improving principal sustainability in large high schools in Oklahoma. Principals recommended having a supportive district administration team, having clear requirements on what after-school events are necessary to attend, increasing staff with an activities facilitator to help with after school events, and also increasing staff to help with behavioral characteristics of some students that are challenges for teachers and principals. Principals also recommended that the hiring process should be done quickly and led by assistant principals and that districts should have alternate educational settings for some students. This research can help district administrators and boards of education implement strategies to increase principal sustainability for principals of large high schools in Oklahoma. [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.]