In this classic text, first published in 1973, Amartya Sen relates the theory of welfare economics to the study of economic inequality. He presents a systematic treatment of the conceptual framework as well as the practical problems of measurement of inequality. In his masterful analysis, Sen assesses various approaches to measuring inequality and delineates the causes and effects of economic disparities. Containing the four lectures from the original edition as well as a new introduction, this timeless study is essential reading for economists, philosophers, and social scientists. In a substantial new annexe, Amartya Sen, jointly with James Foster, critically surveys the literature that followed the publication of this book, and also evaluates the main analytical issues in the appraisal of economic inequality and poverty.