This article from the National Association of Secondary School Principals emphasizes the critical role of high-quality principal development in improving outcomes for students, teachers, and schools. The article interviews Marjorie Wechsler from the Learning Policy Institute (LPI) and explores LPI's report Developing Effective Principals: What Kind of Learning Matters?. The article highlights the need for principals to learn about instructional leadership, data-informed decision-making, collaborative work environments through internships, expert mentors, and collaborative networks. The research underscores the evolving role of principals, with new and veteran principals alike expressing a desire for professional development across various topics. Additionally, access to high-quality preparation, internships, and mentoring significantly impacts principal retention, and districts can support principals by offering convenient professional development and embedding it into evaluation and mentoring systems. This resource emphasizes equity, urging increased access to quality learning opportunities for all principals.