Scholars of leadership have infrequently addressed the diversity of leaders and followers in terms of culture, gender, race and ethnicity, or sexual orientation. This omission has weakened the ability of research and theory to address some of the most provocative aspects of contemporary leadership, including (a) the limited access of individuals from diverse identity groups to leadership roles; (b) the shaping of leaders' behavior by their dual identities as leaders and members of gender, racial, ethnic, or other identity groups; and (c) the potential of individuals from groups formerly excluded from leadership roles to provide excellent leadership because of their differences from traditional leaders. In addressing such issues, we argue that the joining of the two bodies of theory and research--one pertaining to leadership and the other to diversity--enriches both domains of knowledge and provides guidelines for optimizing leadership in contemporary organizations and nations.