This research report from The Wallace Foundation suggests that with better aligned training and development, assistant principals could make more significant contributions to advancing equity, improving schools, and supporting principal effectiveness. Based on a synthesis of 20 years of research on assistant principals in U.S. public schools, the authors, researchers at Vanderbilt University/Peabody College of Education and Mathematica Policy Research, find that while the number of assistant principals in schools has increased over the past 25 years, their role is often overlooked and underdeveloped. The authors note that the job of the AP is complex and although it is an increasingly common step toward a principal position, not all APs  are assigned responsibilities that best prepare them to become principals. Furthermore, the study finds racial and gender disparities in the school leadership pipeline as well as evidence that AP evaluation is often disconnected from their role and responsibilities.