The Introduction maps out the book’s central arguments, contribution, and structure, in addition to contextualising key issues and providing essential background information. It considers the relevance of science diplomacy for understanding China’s international scientific relations under Mao and, in turn, the ways those activities deepen our understanding of the range of actors and approaches involved in science diplomacy. Important ideological concepts and foreign relations strategies underpinning these outreach activities, particularly ‘united front work’, were central to the CCP’s outreach practices involving scientists. The chapter further considers the importance of transnational science in modern China and international science in the post-Second World War period, as well as introducing the key scientists, organisations, and events that sit at the centre of this study.