In 1983 Australia experienced unexpected nation-wide increases in enrollment in post-compulsory schooling (Year 11 and Year 12). This study sought to identify factors contributing to this increase, to assess the extent and characteristics of the change, and to examine the motivations and expectations of the students concerned. Patterns of school retention were considered in relation to the influences of the economic environment, the social-psychological environment, and the school environment on individual decisions to remain in school. Data were analyzed on three levels: school systems, schools, and students. Chapter 2 outlines the study's design and methodology. Chapter 3 describes the patterns and trends in government school systems retention, their relationship to non-government schools and to opportunities in equivalent programs through Technical and Further Education. Chapter 4 examines differences between schools in retention rates and the types of recent program developments occuring in schools. Chapter 5 and 6 report on students' reasons for staying in or leaving school and their intentions for further study. Chapter 7 reviews the findings on factors influencing retentivity in Australian government secondary schools. Appendices contain detailed information on the retentivity measures, two student questionnaires, and the school curriculum and organization questionnaire. (BS)