This book is based on the author's published research and uses the principal-agent methodology as a consistent framework for analysing and evaluating the development of the European Union's agricultural land use policy as it has evolved over the last two decades from voluntary set-aside to 'compliance' set-aside to environmental stewardship. The book begins with an introduction to the principal-agent methodology and to the historical development of agricultural land use policy in the CAP (Common Agricultural Policy). There are also literature-based introductions which contextualise each major part of the book (Parts A and B). The book concludes with some reflections and forward-looking comments on policy design lessons from this research, which will be of use to students, academics and policymakers.