Technological change--the advance in knowledge relative to the industrial arts--is an important, if not the most important, factor responsible for economic growth."" The author is Professor of Economics at the Wharton School, University of Pennsylvania, consultant to the RAND Corporation, the Federal Power Commission, and the U.S. Army. Professor Mansfield provides an in-depth analysis of the relation of technological change to productivity growth, industrial research and development, innovation and the diffusion of new techniques, automation and labor displacement and adjustment problems, government expenditures on R and D (the federal government finances two-thirds of all R and D, one-half of the federal expenditure is made by the Department of Defense); public policy and technological change. While intended for the nonspecialist, this is close reading for interested parties rather than the casual reader.