Students in our nation's largest school systems--a majority of whom are students of color from nondominant communities--are unlikely to attend schools with strong, consistent leadership. Those big-city school systems are increasingly adopting principal pipeline initiatives to address the quality and stability of their principal corps. Principal pipeline initiatives (pipelines) aim to align, tailor to a district's needs, and codify how principals are developed throughout their career in a district. Existing research suggests career-long, coherent, and district-led pipeline models hold promise but also that they are challenging to implement, since pipelines demand districts fundamentally shift how they have typically developed principals in disjointed ways. Reports on pipeline implementation and evaluation describe what pipelines can look like and show initial positive impact on principal turnover and student outcomes across several school districts. However, this nascent literature does not yet explore who is leading these change efforts within school systems and how those leaders are putting pipeline initiatives into practice day after day--nor does it conceptualize the process of pipeline implementation. This study draws on Organizational Learning and Organizational Sensemaking Theories to frame pipeline implementation as persisting in a complex change process towards ambitious equity goals. This embedded qualitative case study used observation-driven methodology to investigate how four intersecting teams of pipeline leaders in one school district maintained attention on improving many aspects of their principal pipeline effort over one year. Findings detail how teams persisted in a process of improvement to different degrees across 19 "cases of improvement," including that leaders did not persist past noticing and naming any issues about pipeline alignment that year. Further, findings depict moves leaders made to support their colleagues to maintain attention on improvement, such as structuring conversations to surface others' lived experiences with an issue and supporting new collective meaning construction. A second set of findings explore conditions that influenced the patterns of persistence in the process of improvement, such as how teams were more likely to persist in improving discrete issues about pipeline programming than interdependent issues about their own teaming. This study contributes to pipeline literature by viewing pipeline implementation as a multifaceted organizational learning process and detailing the daily leadership it takes to persist in such a complex process over time. Findings suggest district pipeline leaders must actively tend to issues that arise at the intersections of pipeline pieces, as well as take a critical eye to the team dynamics and forms of collaboration at work on their pipeline teams. [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.]