Ariel Pakes is the Steven McArthur Heller Professor of Economics in the Department of Economics at Harvard University, where he teaches courses in Industrial Organization and in Econometrics. Before coming to Harvard in 1999, he was the Charles and Dorothea Dilley Professor of Economics at Yale University (1997-99), and before that he held tenured positions the University of Wisconsin (1986-88), and the University of Jerusalem (1985-86). Pakes received his doctorate degree from Harvard University in 1980, and he stayed at Harvard as a Lecturer until he took up a position in Jerusalem in 1981. Professor Pakes' research has been in Industrial Organization (I.O.), the Economics of Technological Change and in Econometric Theory. He and his co-authors have recently focused on developing techniques that allow us to empirically analyze models of market interactions. This includes methodological work on how to estimate demand and cost systems and then use the estimated parameters to analyze equilibrium responses to policy and environmental changes, empirical work which uses these techniques to analyze the implications of alternative events in different industries, and the development of a framework for the numerical analysis of dynamic oligopolies (with and without asymmetric information and with and without collusive possibilities).