I have been reading alot of books recently on leadership and one which has really informed my thinking is The New Psychology of Leadership: Identify, Influence and Power by Alexander Haslam, Stephen Reicher and Michael Platow. The basic premise is that effective leadership is all about influencing others so they are motivated to achieve goals. It really highlights the importance of followership, social identity and how leadership is bestowed on us by other people. Well worth a read.