The impact of childhood trauma on students in schools has become a relevant issue for today's school leaders in the United States (Mendelson et al., 2015). The effects of trauma often interfere with students' ability to learn and manage the demands of a school environment. Students are coming into schools with diverse academic, behavioral, and social-emotional needs, which has led school leaders to adopt trauma-informed approaches and programs in schools (Rossen, 2020). There are many trauma-informed programs available to school principals, one of them being the Neurosequential Model in Education (NME). This particular approach connects trauma-informed practices to neurobiological principles to allow school principals to adapt and adjust the approach to meet the needs of their school and students. The purpose of this collective case study was to understand how principals in a school district led the integration of the NME approach in their schools. Three principals from one school district in a western state were interviewed who worked in three different schools. Seven licensed staff members were interviewed in three focus groups. The staff members included five teachers, one instructional coach, and one social worker. These individuals all worked at a school led by one of the principal participants. Relevant documents were collected from the three schools. The findings from the interviews, focus groups, and documents were compared to scholarly literature on trauma-informed school leadership, transformational leadership theory, and contemporary trauma theory. This study found that principals integrated NME by integrating it into existing systems, by prioritizing self-regulation, being responsive to individuals, and by modeling the way. One principal saw the NME approach as an opportunity to refine current systems in his building to be more neurobiologically and trauma informed. All three principals prioritized self-regulation for their staff and for their students. The three principals also led the integration of NME by being highly responsive to their staff and their varying needs and skills. Lastly, all three principals modeled the way in which they expected staff to integrate the principles of NME. A key finding from this study was the customizable nature of the NME approach. The findings from this study may support new and existing school and district leaders who are hoping to adopt NME or a similar trauma-informed approach. Policymakers may benefit from the knowledge that principals and school districts need flexibility to integrate the NME approach based on their school and district's particular needs. [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.]