This collection of writings provides the only comprehensive introduction to the input-output model for which Leontief was awarded the Nobel Prize in 1973. The structural approach to economics developed by Leontief, and known as input-output analysis, paved the way for the transformation ofeconomics into a truly empirical discipline that could utilize modern data processing technology. This thoroughly revised second edition includes twenty essays--twelve of which are new to this edition--that reflect the past developments and the present state of the field. Beginning with anintroductory chapter, the book leads the reader into an understanding of the input-output approach--not only as formal theory but also as a research strategy and powerful tool for dealing with a complex modern economy.