Catholic schools represent the major alternative to government schools in providing formal primary and secondary education for the Australian school-going population. The organisational structure of the Catholic school "system", however, differs significantly from that of government systems. Traditionally, Catholic schools form a decentralised network of administrative and governing authorities. Within this tradition, there are difficulties in developing a conceptual model fur a state or national view of Catholic school structures. During the past couple of decades, changes of a sociopolitical, economic, and ecclesiastical nature have caused public and private education authorities in Australia to view Catholic schools in an aggregated as well as individual sense. Along with increased public subsidies for the establishment and operation of schools, public accountability ana scrutiny for fiscal and other policy development purposes have likewise grown. The future of the Catholic school system is therefore of interest to both government agencies and Catholic authorities. To facilitate an analyses of the broad future for a school system, one useful tool is a model of the system which can be used to project enrolments. Enrolment projections in the very best of organisationally structured environments are precarious predictors of the future, so the business of applying a projection model to base data requires qualification. Since Catholic schools form an irregular organisational pattern which is undergoing change, projections of Catholic school enrolments at state or national levels in Australia require particular qualification. This study is mainly concerned with the development of a model for projecting Catholic school enrolments. It is aimed at taking advantage of data produced by the 1976 Australian Census of Population and Housing when this becomes available. However, it also analyses the historical development of Catholic schools in a general sense, and looks to a number of social, political, and economic trends which may act as pointers towards future developments.