This is the first of five ambitious volumes theorizing the structure of governance above and below the central state. This book is written for those interested in the character, causes, and consequences of governance within the state and for social scientists who take measurement seriously. The book sets out a measure of regional authority for 81 countries in North America, Europe, Latin America, Asia, and the Pacific from 1950 to 2010. Subnational authority is exercised by individual regions, and this measure is the first that takes individual regions as the unit of analysis. On the premise that transparency is a fundamental virtue in measurement, the authors chart a new path in laying out their theoretical, conceptual, and scoring decisions before the reader. The book also provides summaries of regional governance in 81 countries for scholars and students alike. Transformations in Governance is a major new academic book series from Oxford University Press. It is designed to accommodate the impressive growth of research in comparative politics, international relations, public policy, federalism, environmental and urban studies concerned with the dispersion of authority from central states up to supranational institutions, down to subnational governments, and side-ways to public-private networks. It brings together work that significantly advances our understanding of the organization, causes, and consequences of multilevel and complex governance. The series is selective, containing annually a small number of books of exceptionally high quality by leading and emerging scholars. The series targets mainly single-authored or co-authored work, but it is pluralistic in terms of disciplinary specialization, research design, method, and geographical scope. Case studies as well as comparative studies, historical as well as contemporary studies, and studies with a national, regional, or international focus are all central to its aims. Authors use qualitative, quantitative, formal modeling, or mixed methods. A trade mark of the books is that they combine scholarly rigour with readable prose and an attractive production style. The series is edited by Liesbet Hooghe and Gary Marks of the University of North Carolina, Chapel Hill, and the VU Amsterdam, and Walter Mattli of the University of Oxford.