This report by researchers from the Universities of Minnesota and Toronto examines the available evidence and offers educators, policymakers and all citizens interested in promoting successful schools, some answers to these vitally important questions. It is the first in a series of such publications commissioned by The Wallace Foundation that will probe the role of leadership in improving learning. As the first step in a major research project aimed at further building the knowledge base about effective educational leadership, available evidence in response to five questions was reviewed. They are: (1) What effects does successful leadership have on student learning? (2) How should the competing forms of leadership visible in the literature be reconciled? (3) Is there a common set of "basic" leadership practices used by successful leaders in most circumstances? (4) What else, beyond the basics, is required for successful leadership? and (5) How does successful leadership exercise its influence on the learning of students? This review of the evidence suggests that successful leadership can play a highly significant--and frequently underestimated--role in improving student learning. This evidence also supports the present widespread interest in improving leadership as a key to the successful implementation of large-scale reform.