In 2015, three economies in China participated in the OECD Programme for International Student Assessment, or PISA, for the first time: Beijing, a municipality, Jiangsu, a province on the eastern coast of the country, and Guangdong, a southern coastal province. Shanghai, which, like Beijing, is also a Chinese megacity of over 20 million people, has participated in PISA since 2009. These four economies alone are home to more than 233 million people – more than the entire population of Brazil, nearly three times the population of Germany and nearly four times the population of France. What do we know about the largest education system in the world? A system that is educating 260 million young people, and that employs 15 million teachers? Not very much. This paper aims to change that. It provides a broad overview of how China’s education system is organised and operates, and how reforms, both past and current, have reshaped education in China over time. The report then examines in greater detail education in the four economies within China that participated in PISA 2015. It provides the context in which China’s participation in PISA – and its results in PISA – should be interpreted.