This book deals with voluntary approaches between farmers and water suppliers as an instrument to meet environmental standards, impacted by agricultural activities, more economically efficient and environmentally effective than by exclusive application of alternative instruments including command-and-control approaches. The book is based largely on the results of the research project 'Co-operative Agreements in Agriculture as an Instrument to Improve the Economic Efficiency and Economic Effectiveness of the European Water Policy', which was supplemented for specific issues by key experts. The research was partly funded by the European Commission under the Specific RTD Programme in the Field of Environment and Climate (Contract No. ENV4-CT98-0782) and partly by the Ministry of Agriculture, Nature Management and Fisheries in the Netherlands, the Environment Agency in England and Wales, the UK Ministry of Agriculture, Fisheries and Food, and the Government of the German Bundesland North Rhine Westphalia. Additional funds for preparing the book were obtained from the Ministry of Agriculture, Nature Management and Fisheries in the Netherlands. The financial and technical support received from the different organisations is gratefully acknowledged. The editors appreciate very much the efforts the authors have made in preparing their contributions for the book and for the secretarial assistance provided by Mrs. Tessa van Dongen from LEI who took responsibility for guiding the publication process and preparing the chapters of the book. We also appreciate the support given by Mrs. Henny Hoogervorst and Mrs. Gloria Verhey (Kluwer Academic Publishers).