The only comprehensive introduction which Leontief has written to his model of Input-Output Economics, for which he was awarded the Nobel Prize in Economic Science in 1972. Many of the chapters have already appeared as articles in journals, but Leontief's writings have a range and consistency that gives this collection a sense of coherence. The book begin with non-technical articles on the theory of Input-Output Economics and progresses to more technical essays, and then to specific applications of the theory. This edition has been thoroughly revised, at least one third of the material being new.