John R. Petrocik is Professor and Chair in the Department of Political Science at the University of Missouri - Columbia. He received his Ph.D. in 1976 from the University of Chicago. His specialty is electoral politics, with particular emphasis on public opinion, voting, and political parties. Petrocik has authored or coauthored books and research articles on mass attitudes and behavior, political parties, and elections and campaigns. One of the books, The Changing American Voter (Harvard University Press, 1976, Revised 1979) received the Woodrow Wilson award in 1977 from the American Political Science Association for the best book on American politics in that year. In a 2008 book with Darron Shaw and Karen Kaufman - Unconventional Wisdom (from Oxford University Press) - he examines (and rejects) several popular myths about American voting and public opinion. Petrocik centers his research on social group dynamics and institutional structures that influence attitudes and behavior of individuals. His recent work has emphasized the social basis of politics and the influence of social divisions on electoral politics.