While much of the business ethics literature highlights the vital role that multinational corporations (MNCs) play in generating economic opportunities and wealth on a global scale, it remains the case that this literature has nonetheless undersold the potential political significance of MNCs. Not only are MNCs amongst the key drivers of international prosperity; they are also perhaps the most durable and conspicuous examples of intensive international cooperation in the world today. Combined with the vast and systemic shortfalls of international justice we observe in the present era, I argue that MNCs’ standing as such gives rise to a series of important ethical obligations that they ought to bear. Specifically, as primary beneficiaries, organizers and instantiations of international economic cooperation, they bear obligations to ensure that the international economic order serves the interests of the world’s worst-off. In this chapter I focus on one subcategory of such obligations, obligations to help ‘inwardly internationalize’ rich, developed states, so that such states are better predisposed to fulfil their existing international obligations. Inward internationalization involves the structural transformation of domestic political and social spaces so that international voices, concerns and obligations are rendered increasingly salient therein. MNCs, I will argue, are particularly well-placed to facilitate familiarity, engagement and constructive dialogue between people across borders, and so to help inwardly internationalize domestic spaces. They have the ability, for instance, to facilitate interactions between workers in their home country and overseas; they have the ability to give overseas workers representation on corporate boards; they have the ability, through advertising and other communications, to highlight to their customers, suppliers and workers the significance of their existing international commercial and ethical ties. In this chapter I argue that they have responsibilities to engage in this sort of ‘internationalizing’ work, and I identify several non-exhaustive ways in which they may do so.