Xavier Sala-i-Martin is a professor of economics at Columbia University. Sala-i-Martin earned his degree from the Autonomous University of Barcelona in 1985 and his Ph.D. from Harvard University in 1990, both in economics. In addition to working at Columbia, he has been a professor at Yale University, Harvard University, and the Universitst Pompeu Fabra in Barcelona (which he still visits for a term every summer).
Sala-i-Martin is widely recognized as one of the leading economists in the field of economic growth and is consistently ranked among the most-cited economists in the world for works produced in the 1990s. His works include the topics of economic growth, development in Africa, monetary economics, social security, health and economics, classical-liberal thinking (with his book "Liberal economics for non-economists and non-liberals") (the "liberal" in the title should be understood in the classic liberal/libertarian sense), and convergence. He has constructed an estimate of the World Distribution of Income, which he has then used to estimate poverty rates and measures of inequality. The conclusions of this study offered a new point of view, for two reasons. First, the United Nations and the World Bank used to believe that, although poverty rates were falling, the total number of poor people was increasing. Sala-i-Martin claimed that both were falling. Second, the United Nations and the World Bank used to (and still do) believe that individual income inequalities were on the rise. Sala-i-Martin claimed they were not.
He is the author of the economic growth textbook Apuntes de Crecimiento Economico (in Spanish) and the co-author (with Robert Barro) of the textbook Economic Growth (original in English and translated into French, German, Spanish, Chinese and Japanese).
Sala-i-Martin is, along with Elsa V. Artadi, the author of the Global Competiveness Index, used since 2004 by the Global Competitiveness Report published by the World Economic Forum, an index that ranks 142 countries by their level of economic competitiveness.