September 12 marks the United Nations (UN) South-South Cooperation (SSC) Day. Celebrated on December 19, 2004 for the first time, the SSC Day was later changed to September 12 to commemorate the adoption of the 1978 Buenos Aires Plan of Action (BAPA) for Promoting and Implementing Technical Cooperation among Developing Countries, which provided the first global framework for SSC. Today, almost four decades since the adoption of the BAPA, SSC has become a significant source of financing and global knowledge exchange. China, as the largest developing country in the world, has been actively engaged in SSC and has become an increasingly important partner for the rest of the developing world.