There is clear consensus that school site leadership is second only to teacher quality in its potential to impact student achievement positively. It is also clear that, despite the fact that principal supervisors can contribute to the effectiveness of site leadership, principal supervision has been a neglected, even haphazard practice in America’s schools. Many principal supervisors in the United States work in relative isolation and experience no professional development designed to support them. Principal supervisors, many of whom have other high-stakes responsibilities ranging from the superintendency to positions in areas such as human resources and curriculum and instruction, have not been asked to make principal development a priority. Principals often only hear from their supervisors when there is a problem, complaint, or operational issue. One