This set provides a definitive scholarly variorum edition of Malthus's Principles of Political Economy. It contains the full text of the first 1820 edition, including Malthus's own invaluable 70-page summary, and contains details of all the additions, omissions, and emendations that occurred between the first and the second, posthumous, edition of 1836. The first edition is extremely rare, and for over 150 years confusions and disagreements have inevitably occurred in the interpretation of Malthus's economics because of the absence of any systematic record of the differences between the two editions. The editor has written a lengthy and authoritative introduction giving an account, derived mainly from contemporary correspondence, of the events and circumstances surrounding the publication of the two editions. It shows the relationship between the Principles and Malthus's other writings and activities as a political economist. there is also an editorial commentary that aims to explain the significance and origin of the alterations.