In his fourth edition of Elements of Theoretical Economics (1900), León Walras introduced the device of written pledges to eliminate path dependency: sellers of products and services write out commitments to supply certain quantities at suggested prices with no commodities actually produced and supplied until a set of prices is found at which supply and demand are equal simultaneously in every market. This brought about very serious alterations to the character of the book. Unfortunately, these changes resulted in an incomplete, internally contradictory, and occasionally incoherent text. This translation, therefore, by two leading scholars of Leon Walras's work, Donald Walker and Jan van Daal, revisits the third edition of this seminal work, including Walras's brilliant explanation of his comprehensive model, with all its richness derived from reality. Growing research into Walras's research indicates that it was this third edition that contained his best theoretical research and a translation of this edition of the book is now a necessity. 'Walras’s theory of general economic equilibrium has inspired many great economists, from Pareto, Wicksell, Fisher, and Schumpeter to Hicks, Samuelson, Arrow, Hahn, and Debreu. It is therefore highly welcome that the third and finest edition of Walras’s opus magnum, Éléménts, for the first time is made available in an excellent English edition thanks to Donald A. Walker and Jan van Daal, two leading Walrasian scholars.' Harald Hagemann, Universität Hohenheim, Stuttgart This is an English translation of the third edition (1896) of Léon Walras' Elements of Theoretical Economics. Donald A. Walker received a Ph.D. in Economics from Harvard University, Massachusetts. He specializes in microeconomic theory and the history of neoclassical economic thought. Dr Walker was the president of the History of Economics Society (1987–8), named Distinguished Fellow of that Society (2006), editor of the Journal of the History of Economic Thought (1990–8), and founder and first president of the International Walras Association (1997–2000). Among numerous other publications, he is the author of two books and many articles on the writings of Léon Walras, including Walrasian Economics (Cambridge, 2006). Jan van Daal received a Ph.D. from Erasmus Universiteit Rotterdam. He has researched and taught in the areas of mathematical economics and published on demand systems, aggregation problems, and the theory and history of general economic equilibrium. Dr van Daal specializes in research on the life and works of Léon Walras and has published, among other writings, The Equilibrium Economics of Léon Walras (with Albert Jolink, 1993), the translation of Walras' Études d'économie appliquée (2005), and the translation of Walras' Études d'économie sociale (with Donald A. Walker, 2010).