This chapter explores the cultural and social aspects of China's cosmopolitan age. Open borders resulted not only in large flows of people moving in and out of the country, but also in active participation in international conferences and international covenants. There is no standard text in English on the diplomatic history of twentieth-century China. The extent to which China was an active agent seeking full participation in the international community — despite a very negative appraisal of its achievements in conventional history — is emphasized. In addition, it looks in more detail at the intellectual links forged at home with the rest of the world by cosmopolitan scholars in virtually every field of knowledge, from avionics to zoology. The existence of an open society allowed controversial styles to be explored, for instance nude photography.