In the 20 years from 1971 to 1990 the percentage of each cohort of young people completing secondary education to Year 12 has more than doubled. Most of that growth in the retention of young people into the postcompulsory years of school has taken place since 1983. In a short space of time postcompulsory schooling has changed from minority to majority participation. Changes such as these have impelled a consideration of how best to respond to the interests and aptitudes of the increasingly diverse population of students and how to encourage further increases in levels of participation. These issues are the central concern of the present study. Various changes have been made in the curriculum and organisational provision for Years 11 and 12 involving the introduction of alternative courses, the broadening of the curriculum range within an existing framework, and incremental changes to existing subjects, courses and teaching methods. Most have been initiated with the intention of improving the quality of education experienced by young people and increasing the holding power of schools. Within this context the present report is concerned with senior secondary schooling in the government high schools of New South Wales. The research project on which it is based was commissioned by the New South Wales Department of School Education in 1987 to inform policy and practice concerning postcompulsory schooling. The project was intended to inform two main issues in postcompulsory schooling: staying at school beyond Year 10, and the quality of the education experienced in Years 11 and 12. It was conceived as a longitudinal study which would follow students over four years of school, from Year 9 to Year 12, and into further education and work. In following those students an emphasis was placed on using the natural variations among schools to explore the contribution of school factors, as well as background influences, to the progress of students.