His research investigates how U.S. labor markets adjust to immigration and to technological change, including how employers adapt their production technology to the local availability of immigrant workers. His newest work investigates the impact of U.S. immigration policies, including legalization. His findings have appeared in top economics journals, including The Quarterly Journal of Economics, the Journal of Political Economy, and the American Economic Journal. Ethan received his Ph.D. in economics from UC Berkeley in 2003.