Recent teacher supervision and evaluation system (TSES) reform efforts have resulted in wide adoption of policies targeting improvements in teaching quality and student outcomes; however, impact of these policies has been inconsistent (Hazi, 2019; Stecher et al., 2018). Failure of TSES efforts to realize their intended outcomes is the result of policy implementation gaps linked to those tasked with their implementation (Shaked & Schechter, 2018; Spillane, Diamond, et al., 2002; Spillane & Kenney, 2012). School principals operate as TSES policy enactors, making sense of and implementing TSES policies; as such, it is vital to examine how principals understand and implement TSES policies. The present study examined how principals in one school district make sense of their district's TSES. Specifically, this study examined how principals enacted their district's TSES and what influenced their decision-making in TSES implementation. Utilizing a multiple case study design, this study used principal interviews that examined what TSES practices they implemented, how they analyzed TSES data, and what evaluation-informed decisions resulted from that data. The sensemaking conceptual framework (Shaked & Schechter, 2017; Spillane, Diamond, et al., 2002; Spillane, Reiser, & Reimer, 2002; Weick et al., 2005) was used to analyze responses. Results suggest general alignment of principal practice and district TSES policies with some areas where implementation varied. Additionally, policy stimuli sources from the district were not a dominant source driving principal's TSES implementation decisions; rather, principals relied on other sources to make sense of TSES policy enactment. Finally, barriers in TSES design, among other factors, impacted principal's TSES implementation. Implications suggest the district should develop a clear TSES vision and supplemental material, model TSES enactment with principals, and continuously improve their TSES. Further, leadership preparation programs should incorporate effective TSES elements and skills necessary for implementation. [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.]