Shortlisted for the CMI (Chartered Management Institute) Management Book of the Year Award 2011--2012! According to John Adair, the most important word in the leader's vocabulary is "we" and the least important word is "I". But if this is true, it raises one important question: why do psychological analyses of leadership always focus on the leader as an individual -- as the great "I"? One answer is that theorists and practitioners have never properly understood the psychology of "we-ness". This book fills this gap by presenting a new psychology of leadership that is the result of two decades of research inspired by social identity and self-categorization theories. The book argues that to succeed, leaders need to create, champion, and embed a group identity in order to cultivate an understanding of 'us' of which they themselves are representative. It also shows how, by doing this, they can make a material difference to the groups, organizations, and societies that they lead. Written in an accessible and engaging style, the book examines a range of central theoretical and practical issues, including the nature of group identity, the basis of authority and legitimacy, the dynamics of justice and fairness, the determinants of followership and charisma, and the practice and politics of leadership. The book will appeal to academics, practitioners and students in social and organizational psychology, sociology, political science and anyone interested in leadership, influence and power.