He is also a Faculty Research Fellow at the NBER and a Research Fellow at IZA. His main research interest is in the economics of education. Other research interests include labor economics, public economics and applied econometrics. Before joining UCI, Clark was an Assistant Professor at Cornell University, a Visiting Assistant Professor at Princeton University and an Assistant Professor at the University of Florida. He completed his PhD at Oxford University and spent two years at the Center for Labor Economics at UC Berkeley.