Private supplementary tutoring, or shadow education, has become a global phenomenon, and China is among the countries where it is most prevalent. By 2019, China's private tutoring industry had grown into a prominent sector providing educational services to millions of students and parents. This article examines the development process of shadow education in China, and explores the path that led to its current prevalence. Drawing on existing literature and publicly available data sources, the article maps key stages of shadow education's evolution and its changing characteristics. The analysis suggests that China's private tutoring industry has undergone three stages of evolution: first, the emergence stage, when small numbers of individuals started to provide tutoring on an informal basis; second, the industrialisation stage, when institutionalised providers became primary providers of more formal types of tutoring services; and third, the capitalisation stage, when major providers of shadow education evolved into part of the educational capital market. The discussion argues that the development trajectory of shadow education occurred in line with the continued marketisation of education in China. The article also addresses the implications of capitalised shadow education as it enters a more intensified and controversial phase of development.