 It is perhaps the only rigorously researched, proven leadership program that districts can deliver themselves, allowing for a wider and deeper impact.NISL is the culmination of an $11 million R&D investment, five years of research and field-testing, and ongoing updates that leverage leading researchers and practitioners from education and other fields.NISL's Executive Development Program emphasizes the role of principals as strategic thinkers, instructional leaders and creators of a just, fair and caring culture in which all students meet high standards.