Underlying the interest in the role of rivalry processes as antecedents to interstate conflict is the simple idea that conflict within the constraints of rivalry works differently than conflict outside of rivalry. Rivalry is by no means necessary for conflict to occur but conflicts associated with rivalry processes erupt with a great deal more historical and psychological baggage than is likely in the absence of rivalry. Rivals have a history of conflict, often over the same issues. Vengeance for past defeats and worries about the probability of future defeats, therefore, intrude into the decision-making processes. Compared to nonrivals, rivals have more reason, whether accurately or not, to mistrust the intentions of their adversaries. They have had time to develop images of their adversaries as threatening opponents with persistent aims to thwart their own objectives. If rivals offer concessions, why should such offers be viewed as anything but attempts at deception? Concessions and movement toward some middle ground, accordingly, are more difficult to attain. The ultimate outcome is that rivals are less likely to settle their disputes than nonrivals. Rivals give themselves fewer opportunities to exit a conflict trajectory, once they are on such a path, than do two opponents coming into conflict for the first time, and, therefore, are also likely to generate more than their fair share of conflict and violence.