â€œCoalition of the willingâ€� is a phrase that we hear invoked with frequency in world politics. Significantly, it is generally accompanied by claims to moral responsibility. Yet the label commonly used to connote a temporary, purpose-driven, self-selected collection of states sits uneasily alongside these assertions of moral responsibility. This article explores how the informal nature of such associations should inform judgments of moral responsibility. I begin by briefly recounting what I call a model of institutional moral agency in order to explain why it seems theoretically and practically problematic to talk about the moral responsibilities of informal associations. I then focus on coalitions of the willing as prominent, and challenging, examples of such associations, before raising misgivings about my own rather stark distinction if it means that accounts of moral responsibility must be reduced to the membersâ€”or potential membersâ€”of such coalitions in a way that neglects the moral significance of their acting together. Prompted by these concerns, I explore arguments by Virginia Held and Larry May about moral responsibility in relation to informal associations and identify insights that can be taken from these positions to refine our expectations and evaluations of the actions associated with such collectivities. Finally, I consider the particular implications of these insights in relation to the widely espoused duty to intervene to rescue vulnerable populations.