Despite reform efforts and calls to accept science as a primary subject in elementary school curriculum and instruction (NRC 2007, 2012), science is still often neglected, deprioritized, minimally taught, or taught through traditional methods where teachers and textbooks are the gatekeepers of knowledge (Banilower, 2019; Banilower et al., 2018; NSTA, 2002; NRC, 2007). In elementary school classrooms, research has found that many factors contribute to the obstacles faced when attempting to engage in science teaching and learning that can be categorized as either an internal or external barrier (Southerland et al., 2007). This study investigates the role of Science Teacher Leaders (STLs) in addressing these challenges within a large NGSS state. Specifically, the research examines how STLs at district and county levels utilize distributed leadership dimensions to navigate internal and external barriers to science reform. Through a comparative case study approach, the study delves into the experiences of STLs across different organizational levels. Using a distributed leadership framework, the study conducts a comparative analysis between county-level and district-level STLs. Findings reveal that organizational levels indeed influence how leadership is enacted. County-level STLs often adopt a broader perspective, engaging in systemic changes and policy alignment across multiple districts. In contrast, district-level STLs provide more hands-on support within their own districts, focusing on teacher development and curriculum management. Overall, the study underscores the critical role of STLs in elementary science reform efforts and highlights the importance of leveraging distributed leadership dimensions to address the complex challenges faced by educators in science teaching and learning. [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.]