Miller is a professor of Government at Claremont McKenna College specializing in California politics, direct democracy, and state constitutional law.
Miller is the Associate Director of the Rose Institute of State and Local Government, a research institute known for its expertise in redistricting, elections, demographic research, and public policy analysis.
In 2011-2012, Miller served as the Ann and Herbert W.
Vaughan Visiting Fellow at Princeton University's James Madison Program in American Ideals and Institutions.