This chapter provides the rationale for policy makers to invest in school leadership policy. It describes the focus of this study, the importance of school leadership and the major challenges countries face in school leadership policy. Effective school leadership is essential to improve teaching and learning within each school and to connect the individual school to the outside world. But school leaders across OECD and partner countries are facing challenges which policy makers need to address. In recent years, the workload of school leaders has expanded and intensified as a result of increased school autonomy and accountability for learning outcomes. As the expectations of what schools should achieve have changed dramatically, countries are seeking to develop new forms of leadership better suited to respond to the needs of rapidly evolving societies. This involves enhancing the capacity of current leaders and preparing and training future leaders.