This paper proposes a Cultural Constructivist approach as a theoretical framework to capture how a state's perceived identity of its significant Other is constituted and evolves through social interactions, and how such identity in turn gives meaning to state interactions or interstate relations. It begins with a literature review and critique on Strategic Culture and Constructivism. While both cultural factors and social interactions are important and intertwined in foreign relations, the two IR streams failed to truly integrate the social and the cultural. The Cultural Constructivist approach is a synthesized theoretical framework of the two for us to better understand the role of culture in social interactions among states. Using China's relationship with Vietnam as a referent point for such analysis, the paper argues that China interacts with its significant Other and perceives it through a culturally unique relationship widely known in the disciplines of anthropology, sociology and cross-cultural psychology as guanxi.