This book integrates decision-making and environmental science. For ecologists it will bridge the gap to economics. For practitioners in environmental economics and management it will be a major reference book. It probably contains the largest collection available of expressions and basic equations that are used in environmental sciences. The authors believe this is the first book on environmental decision analysis that includes chapters on ethics, aesthetics as well as life quality. The book is organized in disciplines, but it also includes 13 applications that draw on all subjects in the book, and where cross-references are extensively used. The applications that range from siting of paper mills to wilderness management show how a range of topics in economics, social sciences and ecology are interrelated when decisions have to be made. The third chapter shows how to carry out a complete environmental screening study in one day.