Introduction: Transformations through Polarization and Global Threats to Democracy - Murat Somer and Jennifer McCoy Democratic Collapse and Return of Old Elites From Illiberal Democracy to Military Authoritarianism: Intra-Elite Struggle and Mass-Based Conflict in Deeply Polarized Thailand - Prajak Kongkirati Democratic Erosion under New Elites Turkey: The Slippery Slope from Reformist to Revolutionary Polarization and Democratic Breakdown - Murat Somer Polarization, Participatory Democracy, and Democratic Erosion in Venezuela's Twenty First Century Socialism - Maria Pilar Garcia-Guadilla and Ana L. Mallen The Political Nature of Ideological Polarization: The Case of Hungary - Federico Vegetti Poland: A Case of Top-Down Polarization - Hubert Tworzecki Democratic Careening and Gridlock Polarization without Poles: Machiavellian Conflicts and the Philippines' Lost Decade of Democracy, 2000-2010 - Aries A. Arugay and Dan Slater United States: Racial Resentment, Negative Partisanship and Polarization in Trump's America - Alan Abramowitz and Jennifer McCoy Dynamics of Polarization in the Greek Case - Yannis Stavrakakis and Ioannis Andreadis Party System Institutionalization and Pernicious Polarization in Bangladesh - Tahmina Rahman The Illusory Promise of Democratic Reform: Success and Failure Polarization in South Africa: Toward Democratic Deepening or Democratic Decay? - Roger Southall Elite Conflict, Compromise, and Enduring Authoritarianism: Polarization in Zimbabwe, 1980 to 2008 - Adrienne LeBas and Ngonidzashe Munemo Conclusions Reflections: Can American Democracy Still Be Saved? - Nancy Bermeo Toward a Theory of Pernicious Polarization and How It Harms Democracies: Comparative Evidence and Possible Remedies - Jennifer McCoy and Murat Somer