The third edition of An Introduction to a Mathematical Treatment of Economics has been extensively revised to make the mathematics more rigorous while still keeping it accessible to beginners. No prior mathematics is assumed. The book starts by using very simple algebra to investigate linear models of micro and macro behaviour. The basic analytical idea of a function is developed and illustrated before calculus is introduced. The economic applications include a thorough-going study of the models of competitive market behaviour and of national income determination as well as an investigation of policy problems in macro economics, the theory of production and the firm, and an introduction to the theory of growth. There are both worked and unworked examples and problems at the end of each chapter, those in the applied chapters being drawn almost exclusively from economics. G.C. Archibald is professor of Economics at the University of British Columbia. Richard G. Lipsey, who is the author of An Introduction to Positive Economics, is Sir Edward Peacock Professor of Economics at Queen’s University, Kingston, Ontario.