Across Europe, the use of negative depictions of immigrants in populist political advertising has dramatically raised. An experimental study explored the underlying mechanisms and boundary conditions for the effects of such ads on explicit and implicit attitudes toward foreigners. Findings disclosed that populist ads reinforced intergroup anxiety and negative stereotypes for voters with lower educational levels. This, in turn, led to more negative explicit attitudes. However, the study observed stronger effects of populist ads on implicit attitudes for individuals with higher educational levels. The necessity of including explicit as well as implicit measures in political communication inquiry is debated.