Grumbach is an associate professor at the Goldman School of Public Policy at UC Berkeley. He was previously associate professor of political science at the University of Washington and a postdoctoral fellow at the Center for the Study of Democratic Politics at Princeton. Grumbach studies the political economy of the United States, with interests in democratic institutions, labor, federalism, racial and economic inequality, and statistical methods. His book, "Laboratories Against Democracy," investigates the causes and consequences of the nationalization of state politics.