Recent studies on the public opinion mechanism of the democratic peace have demonstrated experimentally that democratic citizens are averse to attacking other democracies. The presence of rivalry, however, has long been recognized as one of the important factors contributing to either initiation or recurrence of international conflict. Despite such importance, our understanding remains limited as to how rivalry affects public opinion, particularly in the context of the democratic peace. In this article, authors Gidong Kim, Yu Bin Kim, and Dongjin Kwak argue that democratic publics’ perception of rivalry weakens the effect of regime type. The authors expect democratic publics to be less reluctant in terms of fighting other rival democracies. Using an original survey experiment in South Korea, they demonstrate that the South Korean public, similar to those of Western democracies, is reluctant to use force against nonrival democracies, but less so against rival democracies. The authors' findings suggest that the scope of the democratic peace should be qualified.