Cristóbal Rovira Kaltwasser is a Professor of Political Science at Diego Portales University in Santiago de Chile and an Associate Researcher at the Centre for Social Confl ict and Cohesion Studies (COES). His publications include Populism: A Very Short Introduction (with Cas Mudde, OUP, 2017), and has published articles in journals such as Comparative European Politics, Comparative Political Studies, Democratization, Government & Opposition, Party Politics and Political Studies. Paul Taggart is Professor of Politics and Jean Monnet Chair, Director of the Sussex European Institute, former editor of Government and Opposition, former editor of the journal Politics, co-convenor (with Prof. Aleks Szczerbiak) of the European Referendums, Elections and Parties Network (EPERN). His publications include The New Populism and the New Politics (Palgrace, 1996) and Opposing Europe? The Comparative Party Politics of Euroscepticism, Vols I and II (co-edited with Aleks Szczerbiak, OUP, 2008). Paulina Ochoa Espejo is an Associate Professor of political science at Haverford College. Her publications include The Time of Popular Sovereignty: Process and the Democratic State (Penn State University Press, 2011) and has publsihed articles in journals such as the American Journal of Political Science, the Journal of Political Philosophy and the Journal of Politics. Pierre Ostiguy is Professor of Political Science and International Relations at the Universidad Católica de Córdoba (Argentina). He has published several book chapters on populism, articles in journals including The Brown Journal of World Affairs (with Kenneth Roberts), POSTData (Argentina), Politique et Sociétés (Québec), and the Revue Internationale de Politique Comparée (Europe) as well as longer texts as Kellogg Institute Working Papers.