John J. DiIulio, Jr. is a Professor of Political Science at the University of Pennsylvania and has won each of Penn's most prestigious teaching awards. He was previously Professor of Politics and Public Affairs at Princeton University. He received his Ph.D. in Political Science from Harvard University. He has been a senior fellow and directed research programs at several leading think tanks including the Brookings Institution and has won awards from the Association of Public Policy Analysis and Management, the American Political Science Association, and other bodies. He has advised presidential candidates in both parties, served on bipartisan government reform commissions, and worked as a senior staff member in the White House. Meena Bose is executive dean for public policy and public service programs in the Peter S. Kalikow School of Government, Public Policy and International Affairs at Hofstra University. She also is director of Hofstra's Peter S. Kalikow Center for the Study of the American Presidency. She received her Ph.D. in 1996 from Princeton University. Dr. Bose teaches courses on the American presidency, presidential leadership and policy making, and American politics. She is the author or editor of several volumes in presidency studies and American politics. She taught for six years at the United States Military Academy at West Point. Matthew S. Levendusky is Associate Professor of Political Science at the University of Pennsylvania. He obtained his Ph.D. from Stanford University, and his B.A. from The Pennsylvania State University. His research focuses on understanding how institutions and elites influence the political behavior of ordinary citizens, including studies of mass polarization, the effects of partisan media, and various other topics. His work has been honored with a number of awards, including the 2011 Jewell-Lowenberg Award (for the best article published in Legislative Studies Quarterly), the 2013 best paper award from the Journal of Politics, the 2014 Goldsmith Book Prize from Harvard University's Shorenstein Center (for How Partisan Media Polarize America), and the 2016 Erik Erikson Early Career Award from the International Society of Political Psychology. James Q. Wilson most recently taught at Boston College and Pepperdine University. He was Professor Emeritus of Management and Public Administration at UCLA and was previously Shattuck Professor of Government at Harvard University. He wrote more than a dozen books on the subjects of public policy, bureaucracy, and political philosophy. He was president of the American Political Science Association (APSA), and he is the only political scientist to win three of the four lifetime achievement awards presented by the APSA. He received the Presidential Medal of Freedom, the nation's highest civilian award, in 2003. Professor Wilson passed away in March of 2012 after battling cancer. His work helped shape the field of political science in the United States. His many years of service to this textbook remain evident on every page and will continue for many editions to come.