This chapter analyzes Sino-American public diplomacy during WWII by focusing on the extraordinary career of Gong Peng – a cosmopolitan young Communist who worked as an interpreter, informal diplomat, and press attaché at the Communists’ Southern Bureau in China’s wartime capital of Chongqing. Due to the exclusion of the Communists from official US-China diplomacy, Gong Peng secured channels for the distribution of international propaganda by cultivating close friendships with the many American journalists, soldiers, diplomats, and intelligence officers who converged on Chongqing during the war. Gong Peng practised public diplomacy by forging an atmosphere of cosmopolitan sociability – a whirlwind of dinner parties and secret rendezvous, late-night meetings and narrow escapes. The informal practices of public diplomacy that Gong Peng developed in wartime Chongqing likewise contributed to the formalization of “people’s diplomacy” as a key element of China’s diplomatic infrastructure after the founding of the People’s Republic of China in 1949.