This What Works Clearinghouse (WWC) report, part of the WWC's School Leadership topic area, examines research on the effects of the National Institute for School Leadership™ (NISL) program on student, teacher, and school leader outcomes. The "NISL" program (formerly the "NISL Executive Development Program") is a professional development program that aims to develop effective, strategic school leaders focused on preparing schools to provide high-quality instruction in a supportive learning environment. No studies of NISL that fall within the scope of the School Leadership review protocol meet WWC standards. Because no studies meet WWC standards, the WWC is unable to draw any conclusions at this time about the effectiveness of NISL on student, teacher, and school leader outcomes.