Cultural differences in aggression are still poorly understood. The purpose of this article is to assess whether a tool for measuring aggression has the same meaning across cultures. Analyzing samples from Spain (n = 262), the United States (n = 344), and Hong Kong (n = 645), we used confirmatory factor analysis to investigate measurement invariance of the refined version of the Aggression Questionnaire (Bryant & Smith, 2001 ). The measurement of aggression was more equivalent between the Chinese and Spanish versions than between these two and the U.S. version. Aggression does not show invariance at the cultural level. Cultural variables such as affective autonomy or individualism could influence the meaning of aggression. Aggressive behavior models can be improved by incorporating cultural variables.