This study examines the implications of the 'equalisation policy' and the expansion of secondary education in South Korea in the late 1960s and early 1970s. The equalisation policy is one of the most radical school reform attempts in South Korea. A random assignment or lottery system for students was introduced for all middle schools in 1968 and all high schools in 1974, abolishing selective and competitive school-based entrance systems. This system was in operation without interruption until the early 1990s when new categories of schools were introduced as a part of South Korea's participation in the global neoliberal school reform movement. The 'second wave of equalisation' since around 2010 and subsequent measures to 're-equalise' schools draw attention to the origin of the equalisation policy and its significance in understanding the development of secondary education in South Korea.