The papers in this volume illustrate the power of a scientific approach to ecological economics. Good science is a careful blend of theory and empirical testing. Theory without empirical grounding is of no practical value and random case studies without a theoretical context are not generalizable. The back and forth interplay between theory and evidence is apparent in the modeling exercises, evaluation studies, and policy design described in this book.Watershed management has been chosen as a concrete focus to illuminate the facets of sustainability. It requires both a deep understanding of th.