1. Introduction. Radical Left Parties in Western Europe and their Electorates: Decline, Transformation and Persistence 2. Explaining Radical Left Parties’ Support: A Framework for Analysis 3. The Social Basis of Radical Left Parties Electorate: Social Stratification and the Radical Left in Contemporary Western Europe 4. Values, Political Attitudes and Policy Positions of Radical Left Parties’ Voters: A Distinctively Progressive Constituency 5. Non-electoral Political Participation and Civic Engagement of Radical Left Voters: A Mobilized Electorate 6. The Effect of the Political, Institutional and Socioeconomic Context: Economic Crises and Political Discontent as Factors Fostering Support for the Radical Left 7. Parties’ Behaviour, Party Competition and Voter Support for the Radical Left: The Importance of Parties’ Policy Positions 8. Conclusion. Explaining Voter Support for Radical Left Parties in Western Europe: The Role of Individual and Contextual Factors