The two most significant events in government secondary schools in Australia between the end of the Second World War in 1945 and the cultural revolution of the late 1960s and early 1970s were the vast expansion in enrolments and the curricular changes entailed, in part, by these. Between 1953 and 1964 four of the six states introduced comprehensive high schools. In the ten years after 1974 the other two states followed suit. In all states the internal structure of comprehensive schools also changed. The examination system, the curriculum, and the provision for higher ability students all came under public scrutiny. This epoch closed with the reforms if 1989-93. Thereafter, comprehensive schools existed in name but lost their dominance and changed their character yet again. The following analysis focuses particularly on New South Wales. After discussing the concept of comprehensive secondary schools, it surveys the long-established system of secondary schooling to which the early comprehensive high schools offered an alternative. Their progress in the six states between 1953 and 1984, is then examined. The cultural transformation of the late 1960s and early 1970s is seen as reshaping the context and nature of comprehensive schooling. The final section examines in some detail the comprehensive system as it operated in Newcastle, New South Wales, from 1953 onwards and the conversion in the 1970s of the specialised secondary schools in the inner city into comprehensives. The study closes with a general survey of the reforms of the late 1980s and early 1990s which relegated comprehensive high schools to a relatively minor position in New South Wales secondary education.