Leadership has attracted the attention of researchers in a wide range of fields, from history to sociology, from military studies to political science, and from business to education (Vroom and Jago, 2007). The study of leadership dates back many centuries, and a large volume of literature has been built up on it. Nevertheless, there are still many gaps in the knowledge on leadership, and many of its aspects have yet to be explained adequately (Conger, 1998; Avolio, 2007). Indeed, there is still no single agreed definition of leadership (Vroom and Jago, 2007; Bennis, 2007), and there continues to be a debate about many aspects of leadership including the best strategies for developing and exercising leadership (Hackman and Wageman, 2007).