Changes in the nature and content of the Secondary Mathematics Program in Australia are revealed by data from two complex studies of mathematics education in that country. This document represents an initial exploration of the information collected, with supplementary analyses by interested researchers invited. In addition to a multitude of tables and figures, sections of this work include chapters on: Changes in the System of Mathematics Education; Data on Populations, Samples, and Administration; Tests and Questionnaires; Characteristics of Students, Teachers, and Schools; Mathematics Achievement of 13-Year-Old Students; Mathematics Achievement of Year 12 Students; Student Attitudes Towards Mathematics; and a section of selected summaries and conclusions. The report also contains four appendices which include: members of the advisory committee and state liaison officers; reproductions of 1978 International Association for the Evaluation of Educational Achievement (IEA) tests A, B, C, D, E and F; and mathematics test item statistics. The document concludes with a list of references. (MP)