Research into leadership effectiveness has largely overlooked the implications of the fact that leadership processes are enacted in the context of a shared group membership, where leaders, as group members, ask followers, as group members, to exert themselves on behalf of the collective. In contrast, the social identity model of organizational leadership, proposed here, emphasizes the characteristics of the leader as a group member, and the leader’s ability to speak to followers as group members. In salient groups with which group members identify, leadership effectiveness rests on the extent to which the leader is prototypical of the group (i.e. representative of the group’s identity) and engages in group-oriented behavior (i.e. behavior perceived to benefit the group). Explicating the added value of our model and going beyond contemporary approaches to leadership effectiveness, we discuss how our model extends, and may be integrated with, three major contemporary approaches to leadership effectiveness (charismatic leadership theories, Leader-Member Exchange theory, and leadership categorization theories). In addition, we outline how our model provides a viable framework to integrate future developments in research on leadership such as a growing attention to leader fairness and the role of emotions in leadership effectiveness.