Biological pesticides based on pathogenic micro-organisms specific to a target pest offer an ecologically-sound and effective solution to pest problems. They pose less threat to the environment and to human health than do chemical pesticides. However, despite the enormous potential for biopesticides, their development, commercialization and use has been slow. The information reported in this book is based on a survey of more than 100 biopesticide research workers in developing countries. The results demonstrate that the main difficulties and constraints facing researchers relate to a lack of expertise in the crucial later stages of development. Biopesticide research is receiving mostly low investments, mainly from the public sector, and requires more multidisciplinary expertise. It is concluded that targeted assistance on a multinational and multi-disciplinary basis is required in developing countries in order to remove the constraints.