This thesis investigates change in secondary schools in South Australia during the 1970s. Public concern about the purposes and organisation of schools and about education in general led to the establishment of a government inquiry in 1969, chaired by Professor Peter Karmel. Its report, Education in South Australia, ushered in a period of rapid change led by the Education Department. High schools and technical high schools were reshaped into comprehensive secondary schools. A significant element in this reform was the human capitalist idea that education is an investment in the development of the individual resulting in social and economic progress. This thesis examines the human capitalist basis of the reforms, the way in which child- centred - open - ideas were used in the reform of the curriculum and the impact of these on the schools. The restructuring of secondary schools into comprehensive institutions necessitated a broadening of secondary curriculum to cater for the more diverse student population. The rigid organisation of student and staff activity was also relaxed. This was known as 'open education' and drew on progressive theories and practices in education. The approach taken was school-based curriculum development, guided by departmental curriculum frameworks. While the Education Department did not specify actual content, it provided frameworks of knowledge, skills and objectives. Schools then developed curriculum suitable for their students. The central theme of this thesis compares the philosophical and practical objectives of the Education Department in introducing these changes with the outcomes in the schools. Finally, this thesis examines how schools were expected to reorganise themselves to connect to the community and the world of the learners in democratic society and design new curriculum. The school- based curriculum development model, which incorporated an emphasis on student needs and intrinsically interesting activities, became the vehicle for the ethos of equality of opportunity and led to curriculum development based on an ideal that learning should be socially and personally relevant. This, and the ideal of democracy, was not effectively defined, resulting in far-reaching consequences for the schools.