How does moral language affect international bargaining? When countries rely on moral language to frame a disputed issue, they decrease the probability of peaceful compromise and increase the probability of the dispute escalating with military action. This language operates through two pathways. First, moral language prejudices domestic audiences against compromise over the disputed issue, thereby limiting the options available to negotiators during bargaining. Second, moral language prompts the dispute opponent to also utilize moral arguments to defend its position. The ensuing moral debate moralizes both sets of domestic audiences, consequently reducing opportunities for compromise and narrowing the bargaining range. Negotiated concessions then frustrate the bargaining opponent and elicit accusations of hypocrisy from domestic audiences for compromising on the principle at stake. This backlash triggers crises and pressures the government to stand firm on its previously principled (and uncompromising) position, increasing the probability of military escalation. An examination of the effects of moral language on negotiation breakdown and dispute escalation in the Falkland Islands/Islas Malvinas case probes the theory. The findings illustrate how moral language can shape a government's behavior far into the future, constraining its ability to broker a peaceful compromise.