The link among the quality of principals, caliber of teaching, and levels of student achievement is a tight one. School leadership is a key factor in the recruitment and retention of quality teachers; teaching quality, in turn, profoundly influences improvements in student learning and achievement. Yet despite their central role in this equation, school leaders have received relatively little policy attention during the past two decades of school reform initiatives. This policy brief, based on the research of Linda Darling-Hammond and her colleagues, is part of a broader effort to bring the central role of principals to the forefront. It describes the major challenges facing the education leadership workforce, reviews existing data about California principals, provides an overview of the state's current principal development efforts, and draws upon research about exemplary programs in other states that could help California policy-makers create a stronger, more cohesive system for preparing and supporting the state's principals, now and in the future. (Contains 2 figures.)