Teaching is widely acknowledged to be the single most important factor related to student learning, but it does not occur in a vacuum. It is structured and supported by a host of organizational factors, effective leadership being foremost among them. Since the turn of the twenty-first century, mounting evidence has confirmed the direct and indirect effect of leadership on school effectiveness and student learning. While there is some broad agreement about what leadership is within organizations, why we need it, and which practices are most successful, there is much less consensus as to how it actually works. Most studies of school leadership continue to focus most often on formally appointed school leaders, principals, or assistant principals, and their actions and behavior. The heroic leader bias refers to a view of leadership that associates leadership activity with individual practices and decision-making, without looking to broader and collective patterns of social interaction or contextual influences of leadership practice.