The Clash of Perceptions offers a novel perspective on and a unique empirical test of one of the most influential, controversial and popular paradigms for explaining international and intergroup conflict: Samuel P. Huntington’s Clash of Civilizations. Huntington argued that alliances and conflicts in the post-Cold War era are determined primarily by cultural identification. Although previous research has found little empirical evidence to support this hypothesis, the fear persisted that due to its popularity the Clash of Civilizations could become a self-fulfilling prophecy. Building on the assumption that (mis)perceptions of intergroup relations can cause real conflicts, Huntington’s core hypotheses are tested for the very first time as a Clash of Perceptions by analyzing empirically the pattern and the determinants of conflict in intercivilizational intergroup perceptions with global survey data. The findings suggest that the Clash of Civilizations may exist after all, if only in our heads.