This case study explored the impacts of school shootings on K-12 school principals. Eleven school principals and assistant principals from rural, suburban, and urban areas in all regions of the United States were interviewed. The study answered two research questions: What impact do school shootings have on school principals? and What do principals recommend to create a climate of positive support for principals related to school shootings? Guided by Cognitive Behavior Theory, findings describe the emotional toll of school shootings, including their thoughts, feelings, and behaviors. Findings include the impact of immediate news of school shootings via social media. Principals made recommendations, including high-quality district support, upgrades to the physical building, professional learning, networking, and political change, to prevent or reduce the frequency of school shootings. High-quality district support includes increased concern for principals and staff and coordinated and prioritized initiatives. Upgrades to the physical building included safety installations (e.g., door alarms, cameras, scanning and/or secure entry vestibules). Professional learning needs included opportunities for principal networking to plan for emergent situations, and ongoing networks of support. Lastly, principals requested political change to reduce or eliminate the frequency and intensity of school shooting incidents. This study contains principals' voices on this topic, which is not prevalent in the current body of research. [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.]