Steven S. Smith is a Professor of Political Science, the Kate M. Gregg Distinguished Professor of Social Science and Director of the Murray Weidenbaum Center on the Economy, Government, and Public Policy at Washington University in St Louis. He has chaired the Legislative Studies Section of the American Political Science Association and has served on the editorial boards of the American Journal of Political Science, The Journal of Politics and Legislative Studies Quarterly. Jason M. Roberts is an Associate Professor of Political Science at the University of North Carolina. He co-edited the book Why Not Parties? Party Effects in the US Senate (2009). His articles have been published in the American Political Science Review, the American Journal of Political Science and Legislative Studies Quarterly. Ryan J. Vander Wielen is an Assistant Professor of Political Science at Temple University. His articles have appeared in Political Analysis, Legislative Studies Quarterly and Public Choice.