This is an English translation of the third edition (1896) of León Walras' Elements of Theoretical Economics. The translators of the work undertook this project for three reasons. First, this edition is Walras's best theoretical work. Second, the two subsequent editions contain new elements that spoil his previous work; furthermore, important parts of the third edition do not appear in the subsequent editions. Third, William Jaffé's translation (1954) of the last edition is now outdated in the light of recent research on Walras's ideas; furthermore, Jaffé's terminology in the parts shared by the third and subsequent editions is not always accurate.