The precautionary principle puts forward the aEURO~commonsenseaEURO (TM) notion that decision-makers should be cautious when assessing potential health or environmental harms in the absence of the full scientific facts. It is now a well-established tenet of environmental law. The debate has turned to its legal implementation, especially its application aEURO~in practiceaEURO (TM). The Precautionary Principle in Practice - Environmental decision-making and scientific uncertainty focuses on these issues. It considers how decision-makers can assess threats to health or the environment when the available scientific evidence is sparse and discusses the types of aEURO~uncertaintiesaEURO (TM) that bring the precautionary principle into play. Peel uses detailed case studies which examine the implementation of the precautionary principle in actual decision-making scenarios: fisheries management; risk assessment for genetically modified organisms; and environmental impact assessment for development applications. She demonstrates an approach that takes account of variable uncertainty issues and can be adapted to different circumstances to ensure a comprehensive assessment of the potential threats to health or the environment.