The ideational approach to populism : concept theory and analysis Populism is on the rise in Europe and the Americas. Scholars increasingly understand populist forces in terms of their ideas or discourse one that envisions a cosmic struggle between the will of the common people and a conspiring elite. In this volume we advance populism scholarship by proposing a causal theory and methodological guidelines a research program based on this ideational approach. This program argues that populism exists as a set of widespread attitudes among ordinary citizens but that these attitudes lie dormant until activated by weak democratic governance and policy failure. It offers methodological guidelines for scholars seeking to measure populist ideas and test their effects. And to ground the program empirically it tests this theory at multiple levels of analysis using original data on populist discourse across European and US party systems; case studies of populist forces in Europe Latin America and the US; survey data from Europe and Latin America; and experiments in Chile the US and the UK. The result is a truly systematic comparative approach that helps answer questions about the causes and effects of populism Textual analysis : big data approaches Kirk A. Hawkins Bruno Paula Castanho Silva Textual analysis : the UK party system Luke March Textual analysis : Croatian presidential candidates Berto Salaj Marijana Grbesa Expert surveys Nina Wiesehomeier Elite surveys Ioannis Andreadis Saskia Pauline Ruth Public opinion surveys : existing measures Steven M. Van Hauwaert Christian H. Schimpf Flávio Azevedo Public opinion surveys : a new measure Levente Littvay Bruno Castanho Silva Ioannis Andreadis Eva Anduiza Nebojša Blanuša Yazmin Morlet Corti Gisela Delfino Guillem Rico Saskia P. Ruth Bram Spruyt Marco Steenbergen Populist mobilization across time and space Hans Georg Betz Populist success in Latin America and Western Europe : ideational and party system centered explanations Simon Bornschier Populist voting in Chile Greece Spain and Bolivia Ioannis Andreadis Kirk A. Hawkins Ivan Llamazares Matt Singer Populist success : a qualitative comparative analysis Bruno Castanho Silva Populism in Spain : the role of intellectuals in Podemos Margarita Gomez Reino Iván Llamazares Valduvieco Populism in Venezuela : the role of the opposition Sahar Abi Hassan Populism in Belgium : nativist cynical perceptions Koen Abts Thierry Kochuyt Stijn van Kessel Populism in the US : the evolution of the Trump constituency Wendy Rahn Activating populist attitudes : the role of corruption Ethan Busby David Doyle Kirk A. Hawkins Nina Wiesehomeier Populist voters : the role of authoritarianism and ideology Rosario Aguilar Ryan E. Carlin