The purpose of this study was to evaluate the Pathway to Leadership in Urban Schools (PLUS) program as implemented in a large urban school district. The program was designed to select and develop school assistant principals (APs) to be more effective at instructional leadership. The study spanned four school years, 2015/16 through 2018/19, and followed three cohorts of newly hired APs during and after their participation in the two-year PLUS residency program. The study evaluated the impacts of PLUS participants on the teachers that they coached during the program and assessed impacts on both teacher retention and on student achievement in teachers' classrooms. The study also evaluated the overall implementation of the program in the district. More than one third of new APs in the district participated in PLUS, and the program influenced the selection criteria for all new APs in the district. Students of teachers coached by PLUS participants had somewhat larger English language arts achievement gains than students of comparison teachers who received business as usual district supports. Teachers whose students had very low achievement gains departed the district at higher rates if they had received coaching and observation from PLUS participants. Most APs viewed PLUS as good preparation for the role of school leader, but some desired additional emphasis in areas other than instructional leadership. [For the technical appendix, see ED606260.]