China recently articulated its ambition to shape the regional and global order and to share the lessons of its own experiences with one-party rule. One of the key actors tasked with implementing this shift in Chinese foreign policy is the International Department of the Central Committee of the Chinese Communist Party (CCP-ID). The CCP-ID maintains the kind of collaborative network that is hypothesized to be a channel of policy diffusion and learning. Offering a first exploration of this under-researched aspect of China’s foreign policy, this chapter systematically compares the activities of the CCP-ID in five of China’s close neighbors to better understand the patterns of interaction and, even more importantly, the topics and content of engagement. Party-to-party relations are used for both promoting China’s foreign policy interests and diffusing authoritarian practices. Our comparison of the CCP-ID’s activities in Vietnam, Cambodia, Myanmar, Mongolia, and Japan suggests that these objectives and the CCP’s cooperation strategies vary considerably across countries, regime types, and domestic power structures.