Threat perception is a powerful tool in international and intergroup conflict. Realists in international relations argue that the perception of threat in intergroup conflict is a function of power asymmetries between groups. In contrast, social constructivists in international relations suggest that a shared sense of identity or similarity can reduce, and in some cases eliminate, perceptions of intergroup threat. Consequently, threat perception might be influenced by both the value similarities and the power asymmetries between the ingroup and the outgroup. In this article, we present an attempt to test empirically how individuals evaluate the similarity of cultural and political values compared with another nation (outgroup) and assess its implications for cooperation among states in the international system. The results of two experiments demonstrate that both power and perceived value similarity play an important role in threat perception among states and discuss implications for future research.