Strategic rivalries are contests between states that view one another as threatening competitors and treat each other as enemies. A disproportionate amount of interstate conflict is generated by a relatively small number of these pairs of states engaged in rivalries that can persist for years. Thus, to understand interstate peace and conflict, it is useful to know how rivalries work in general and more specifically. In the past two decades, a strenuous effort has been mounted to introduce the concept of rivalry and demonstrate its utility in unraveling conflict situations. Yet all...