The 1964 Peking Science Symposium and 1966 Summer Physics Colloquium were the two largest-scale international science congresses hosted by Mao’s China. Chapter 4 delves into the inner workings of these events, which brought hundreds of visitors to the People's Republic of China from throughout Asia, Africa, Latin America, and Oceania. From planning through to post-conference tours organised for participants, it examines the network of organisations and individuals at national and local levels that collectively shaped these major initiatives to bring foreign scientists to China on the cusp of the Cultural Revolution. In doing so, it shows the extent of integration and coordination between science and foreign relations systems during the Mao era.