This book explains how ideology can be better integrated into economic history analysis, arguing that if economists and economic historians are to fully understand economic behaviour a much deeper appreciation of ideological processes is required. The book has two parts. The first part presents a comprehensive theory of ideology and ideological change that can be easily incorporated into economic analysis; the second provides an empirical case study of ideological change from East Germany of the 1960s.The book demonstrates how current restrictive views of ideology found within mainstream economics can be enhanced by adopting a more expansive, multidisciplinary understanding of ideology and its role in the processes of economic change. Merging a view of ideology as a fluid and politically practical concept with the framework of change offered by institutional economics, the authors use this theory to provide an in-depth analysis of how the ideological case for the New Economic System in East Germany and for de-Stalinisation more generally in the 1960s was built. Rich in archival material, the book both deepens our understanding of economic change in the communist world in the post-Stalin era and demonstrates the multifaceted role of ideology in economic decision making. With a cutting-edge approach, this book will be a valuable resource for students of economics, economic history, political economy, as well as of communist and German history.