Antisemitism, characterized by prejudice, discrimination, and hostility toward Jews, is marked by two enduring paradoxes. First, although people typically defer to powerholders, perceptions of Jews as powerful are associated with disdain rather than deference among antisemites. Second, antisemitism emerges among individuals with opposing ideological worldviews, those who strongly support societal hierarchies and those who vehemently oppose them. To explain these paradoxes, we introduce the dual-threat model of antisemitism, which highlights the central role of perceived Jewish power in fueling antisemitism. The model posits that perceived Jewish power—defined as perceived control over valuable resources—elicits two distinct types of threat. For proponents of hierarchy, perceived Jewish power threatens ingroup dominance, challenging their desire to maintain group superiority. For opponents of hierarchy, perceived Jewish power threatens egalitarian ideals, undermining their vision of a fair and equal society. Evidence from the United States, Mexico, Australia, the United Kingdom, Germany, and Poland lends cross-cultural support to the model. We discuss the implications of the model and the empirical evidence for designing interventions aimed at curbing antisemitism.