José Antonio Cheibub is Associate Professor and Harold Boeschenstein Scholar in Political Economy and Public Policy at the University of Illinois, Urbana-Champaign. He earned his Ph.D. from the University of Chicago and has previously taught at the University of Pennsylvania and Yale University. He is a co-author of Democracy and Development: Political Institutions and Well-Being in the World, 1950–1990 (Cambridge, 2000), which won the 2001 Woodrow Wilson Foundation Award given by the American Political Science Association. He is also a co-editor of the Democracy Sourcebook (2003). Professor Cheibub has published articles in numerous edited volumes and journals, including Annual Review of Political Science, the British Journal of Political Science, Comparative Political Studies, the Journal of Democracy, and World Politics.

• 1. Introduction; 2. Presidential, parliamentary, and mixed democracies; 3. Are the incentives for coalition formation different in parliamentary and presidential democracies?; 4. Are coalitions rare in presidential democracies?; 5. Party discipline and form of government; 6. What makes presidential democracies fragile?; 7. Conclusion.