It is widely accepted that principals are vital to school success, but few studies have closely examined how to train effective school leaders. Now, a report has identified the common features of exemplary programs for preparing principals who can guide instruction and foster school improvement. The study examined eight programs, chosen on the basis of expert recommendations, that represented a variety of approaches to preservice and in-service preparation and had evidence on effectiveness as shown by the quality of their graduates. It was prepared by researchers at Stanford University in collaboration with the Washington-based Finance Project, a policy-research group. Linda Darling-Hammond, the lead author of the report and a professor of education at Stanford, has said that the findings show that high-performing principals are not just born, but can be made. The bad news, she said, is that most states lack the infrastructure to support such programs.