Our disquisition is founded in both the leadership literature and empirical data from four North Carolina school districts. Our work and the literature suggest that support is needed for assistant principals to develop their leadership capacity and prepare them for the principalship (Chan, Webb, & Bowen, 2003; Leithwood, Louis, Anderson, & Wahlstrom, 2004). We utilized improvement science methods to identify a problem of practice to be addressed with an improvement initiative (Bryk, Gomez, Grunow, LeMaheiu, 2016). Our improvement initiative was employed through a combined framework of succession planning (Lynn, 2001; Peters, 2011) and social justice leadership theory (Theoharis, 2007; 2009). Called the Assistant Principal Professional Leadership Experience (APPLE), our implementation consisted of three components including an orientation session, monthly professional development sessions, and shadowing experiences. Utilizing a PDSA (Plan-Do-Study-Act) approach, we collected data throughout the initiative to make decisions. Using both qualitative (interviews, focus groups) and quantitative instruments (surveys), we analyzed the pre-initiative and post-initiative data to find statistically significant growth in several leadership areas, including: equity, student assessment, teacher evaluation, teacher remediation, data-driven decision making, student decision making, and school safety. The data showed mean increases in assistant principal created goals as well as increases in the pre- and post-measurements of the North Carolina Standards for School Executives. The qualitative and quantitative shadowing data showed positive findings that acknowledged the success of the experience.