The ideational definition of culture has hindered a meaningful debate of the role that culture plays in the discipline of International Relations. Focusing on the behavior side of culture instead, this paper proposes the Cultural Constructivist approach that takes account of both the cultural and the social in interstate relations. Academic puzzles in contemporary China's relations with Japan, the former Soviet Union, and the United States are better explained by taking into account China's cultural behavior pattern and its role in the country's identity construction of these other states. Cultural Constructivism is a falsifiable theory that enables us to see under which circumstances culture intervenes in a country's foreign policy making. A cultural behavior pattern has complicated the PRC's relations with Japan and the former Soviet Union, but material constraints and cultural differences prevented its ascendance to the main stage of Sino–US relations.