This book combines historical and policy-oriented perspectives on the relevance of the Keynesian approach for economic theory, policy, and crisis analysis. The first part focuses on historical, theoretical, and methodological issues, and puts them in context with current developments. The second part focuses on the application of the Keynesian approach to modeling the economy, policy-making, and analyzing the ongoing crisis of the early 21st century. Bringing together contributions by leading macroeconomists such as Laidler, Cukierman, Colander and Boyer, and leading historians of economics such as Hollander, Boianovsky, Marcuzzo, Dimand, Witztum, Young, deVroey and Arnon, the book offers a comprehensive overview of Keynesian economics today. One of the books most essential features are the commentaries on the papers, which promote a cross-fertilization between macroeconomists and historians of economics, providing, in conjunction with the papers themselves, a balanced outlook on the current relevance of Keynesian economics.