While many nations express a commitment to improved educational quality, education often slips down on the policy agenda. Because the benefits of educational investments are seen only in the future, it is possible to underestimate the value and the importance of improvements. This report uses recent economic modelling to relate cognitive skills--as measured by PISA and other international instruments--to economic growth. This relationship indicates that relatively small improvements in the skills of a nation's labour force can have very large impacts on future well-being. The second section of this report describes analyses of human capital and economic growth. It provides a short review of alternative models of economic growth and links these to the progression of empirical analysis. From this, it summarises the best evidence on how cognitive skills affect economic growth. The third section then presents a series of simulations for OECD (Organisation for Economic Cooperation and Development) countries of various amounts of improvement in cognitive skills. The fourth section concludes and discusses some of the political-economy issues involved. Technical issues, including the development of measures of cognitive skills and the underlying statistical modelling, are presented in annexes. (Contains 8 tables, 11 figures, 2 boxes, and 35 notes.) [This paper was produced by the Indicators and Analysis Division of the OECD Directorate for Education.]