Shared leadership entails a dynamic, interactive influence process among groups and teams. Whereas traditional models of leadership emphasize the importance of vertical leadership as a role occupied by an individual in a designated position, shared leadership emphasizes the importance of leadership as an unfolding social process, shifting the influence to the person with the most relevant knowledge, skills and abilities, juxtaposed against the emerging task related requirements. Research shows that shared leadership is a robust predictor of group, team and organizational outcomes across a variety of organizations, industries and cultural contexts. In fact, shared leadership is a better predictor of outcomes than vertical leadership. This Element provides a comprehensive review of the research on shared leadership, and points to promising directions for the future, in terms of both research and the practical application of shared leadership in action. This title is also available as Open Access on Cambridge Core.