Principals have a strong role to play in forming school cultures that encourage change. Changing a school's culture requires shared or distributed leadership and instructional leadership. A multiyear study found that three elements are necessary for a school culture that stimulates teachers to improve their instruction: 1) Teachers and administrators need to engage in deeper organizational learning, 2) teachers need to be part of a professional community, and 3) change requires trust between teachers and administrators, among teachers, and between teachers and parents.