This paper looks at the central role of school leadership for developing and assuring the quality of schools, as corroborated by findings of school effectiveness research and school improvement approaches. Then, it focuses on the growing importance placed on activities to prepare school leaders due to the ever-increasing responsibilities they are facing. In many countries, this has led to the design and implementation of extensive programs. In this paper, international trends in school leader development are identified. As regards the aims of the programs, it becomes obvious that they are increasingly grounded on a more broadly defined understanding of leadership, adjusted to the core purpose of school, and based on educational beliefs integrating the values of a democratic society. (Contains 2 notes.)