Crisis communication systems (CCS) in educational settings have been challenged by mass casualty events including shootings, natural disasters, and health outbreaks in the United States. The U.S. federal government and the U.S. Department of Education have created safety and security instructions to manage these complex and diverse security issues, yet they do not address the role of school leaders within a CCS. Using complex adaptive systems as the theoretical construct, the purpose of this qualitative case study was to examine CCSs utilized by school leaders within a single public school district in the United States. The research questions are focused on the influence of components in a CCS, CCS influence on safety and security, and the school leader's role. Data were collected through interviews with 20 school principals and assistant principals of the school district. Interview data were inductively coded and subjected to thematic analysis. Findings indicate that approximately 40% of interviewees believe that communication behavior was the most critical component in a CCS. Methods of communication are varied and include a combination of technologies and behaviors. In addition, the majority of participants reported that internal decision making used by human agents in a CCS influences safety and security in an educational environment. The positive social change implications stemming from this study include recommendations to the school district to enhance communication systems with both human and nonhuman methods, which may contribute to creating safer educational settings for students, faculty, and communities. [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.]