His research interests are federal tax and expenditure policy, state and local public finance, and the construction and simulation of computable general equilibrium models. His current research focuses on the economic effects of corporate tax reform, the economic and distributional effects of fundamental tax reform, individual portfolio allocation in the 2000s, and various other tax policy issues.

He is co-editor of “Fundamental Tax Reform: Issues, Choices and Implications” (The MIT Press, 2008). Diamond is the forum editor for the National Tax Journal and has served on the Joint Committee on Taxation, United States Congress (2000-2004). He has also served as a consultant on the efficacy of structural adjustment programs to the World Bank. He received his Ph.D. in economics from Rice University in 2000.