This research study focused on the intersection of three important aspects of public education--district policy, school-level leadership, and racial achievement gaps. The study examined the influence of school-level leadership in the implementation of a specific, district-wide policy designed to reduce racial achievement gaps through changes in instructional practices. School leadership represents a powerful tool for improving student performance because research shows that school leaders can impact student achievement (Hallinger & Heck, 1996; Leithwood, Seashore Louis, Anderson, & Wahlstrom, 2004; Leithwood & Seashore Louis, 2012; Witziers, Bosker, & Kruger, 2003). This study focused on elementary schools because of the key role elementary school principals serve as instructional leaders (Bryk et al., 2010, Witziers et al., 2003). To evaluate the effects of school-level leadership in the implementation of the Learning-Focused Schools instructional planning model, the study focused on a subset of seven elementary schools within the district that had consistent principal leadership over the course of the initial implementation period. Using the conceptual framework of implementation science, the study investigated the strategic agency of the principal during the implementation process using a mixed methods design. The study did not find improvement at the district level in overall academic performance as measured by grades 3-5 test data in reading and math from implementation of the model, but did find reductions in some achievement gaps. The individual school results varied substantially both in terms of overall academic performance and the performance of different subgroups. A case study approach was used to highlight the three schools that saw gains in both subject areas. While common themes emerged across the implementations, the interviews and implementation plans reflected the individual choices made at the school level. Understanding the different ways in which principals influence the implementation process is important for both district leaders and school leaders; successfully leveraging the power of the principal could represent a potentially powerful tool for districts in achieving instructional change within schools. [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.]