What interests do states have in assisting and protecting vulnerable populations beyond their borders? While some political leaders and commentators promote a circumscribed understanding of the national interest that rules out accepting substantial risks and costs for the sake of the distant vulnerable, others endorse an enlightened conception of the national interest that recognizes the long-term utility to be gained by helping them. However, while this notion of enlightened self-interest gives states reason to act in some instances, it fails to prompt action in other cases where the suffering of strangers is less strategically important. Some leaders and commentators have responded to this problem by reaching for some other, less material conception of the national interest to justify assisting the distant vulnerable, but they have often struggled to find the language they need. This article finds a solution in the debates about self-interest waged in seventeenth-century Europe. Dissatisfied both with Hobbes's narrow understanding of self-interest and Pufendorf's more enlightened understanding, Leibniz defended a more generous and disinterested conception, grounded not in considerations of material utility but in the pleasure to be derived from helping those in need. This article demonstrates two ways in which this disinterested conception of self-interest can be of use today. First, it provides resources for explaining why states already sometimes act in disinterested and altruistic ways. Second, it provides leaders with a tool for persuading people to help the distant vulnerable, even when it appears to be in neither their narrow nor their enlightened interests to do so.