Childhood exposure to adversity is prevalent, with most individuals in the United states having experienced at least one adverse event in childhood (Child and Adolescent Health Measurement Initiative, 2019; Merrick et al., 2018). Low dosages of childhood adversity experienced within the context of a safe and caring home environment can promote the development of healthy coping skills that prepare children for future adversity. However, childhood adversity that is intense, chronic, or complex can result in a toxic stress response that leads to the development of mental illness, physical health concerns, cognitive deficits, academic performance deficits, and in severe cases, premature death (Berens et al., 2017; Blanchette & Caparos, 2016; Brown et al., 2009; Ehring & Quack, 2010; National Scientific Council on the Developing Child, 2014; Nelson et al., 2020). Given these severe consequences, interrupting the pathways from childhood adversity to psychosocial dysfunction is critical, as is promoting the pathway from adversity to resilience. Accordingly, over the past 20 years there has been a substantial push for schools to be part of this effort by becoming "trauma sensitive." Trauma-sensitive schools realize the prevalence of childhood adversity among their students and staff, recognize the symptoms of trauma, respond effectively, and avoid re-traumatizing students. There currently exists a diversity of approaches, implementation methods, and measures of effectiveness for trauma-sensitive school initiatives, making it difficult to draw conclusions about the overall effectiveness of this approach. This study aimed to determine the effectiveness of the trauma-sensitive school approach by conducting a meta-analysis of existing empirical evidence. The scope of this meta-analysis was focused on the following research questions: Q1. Do trauma-sensitive schools positively impact student, staff, and school-climate outcomes? Q2. What are the specific components of trauma-sensitive schools that make them effective? Q3. What are the ideal dosages for staff professional development and overall intervention? Overall, staff outcomes appeared to improve in both longitudinal and cross-sectional studies. Student outcomes improved longitudinally but not cross-sectionally. Similarly, school climate improved in longitudinal but not cross-sectional studies. Interestingly, staff reported significantly greater improvements in school climate than students. Regarding research question two, no differences in staff or student outcomes were found based on the number of trauma-informed elements included (i.e., professional development, organizational change, trauma-informed practice change). Aggregate effect sizes also did not significantly vary by dosage of trauma-informed professional development. However, is important to note that the methodology of the included studies severely limited the ability to draw strong conclusions about the impact of trauma-sensitive schools. Most longitudinal studies did not include control groups, over a third of outcome measures were either unvalidated or had mixed results for validity, and random assignment to condition was not common. Future directions for this body of research include prioritizing methodologically rigorous studies and examining individual-level moderators (e.g., gender). Despite these limitations, this meta-analysis marks an important step in synthesizing the available data on trauma-sensitive schools and results indicate that continued investment in trauma-informed schools is warranted. [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.]