Following the original initiative of the International Organisation for Biological Control some 15 years ago, research groups and agrochemical companies have been investigating the effects of pesticides on beneficial organisms, devising laboratory and field test methods and lately developing prools for regulatory testing requirements in Europe. This work, and the application of agreed prools for testing, is of crucial importance to the environmentally acceptable use of pesticides and to the further development of Integrated Pest Management systems, and the objective of this book is to review the origins and progress of the research - what has been accomplished, what is the current position and what still needs to be done.