ABSTRACT:The primacy of shareholder demands in the traditional theory of the firm has typically excluded marginalised stakeholder voices. However, shareholders involved in social shareholder engagement purport to bring these voices into corporate decision-making. In response to ethical concerns about the legitimacy of SSE, we use the lens of discourse ethics to provide a normative analysis at both action and constitutional levels. By specifying three normative questions, we extend the analysis of SSE to identify a political role for shareholders in pursuit of the common good. We demonstrate the desirability for SSE to promote regulatory/institutional change to guarantee marginalised stakeholders a voice in corporate decisions that affect them. The theory of SSE we propose thus calls into question the stark separation of the political and economic spheres and reveals an underlying tension, often overlooked, within the responsible investment literature.