Managing environmental contamination requires decision makers to weigh eXlstmg risks against the potential effects of implementing environmental policies - considering both the benefits and disruptions that may result from different actions. The NATO Advanced Research Workshop in Lisbon was an important step in the development and application of cost efficient methods of risk assessment especiaIly within the constraints of a budget. The goal of the workshop was to evaluate the potential for risk assessment to serve as a unified and unifying technique in addressing a wide range of environmental problems. Papers presented in this book discuss issues ranging from specific and local studies (specific site, ecosystem, pollutant) to global decision and management frameworks (watersheds, regions, integration of multiple poIlutants and stressors); they develop a range of approaches starting from specific methods to widely applied public policies (Figure 1). The papers show that the use of risk assessment can provide the scientific basis for environmentaIly sound and cost-efficient policies, strategies, and solutions to our environmental chaIlenges. The organization of the Proceedings reflects sessions and discussions during the workshop. The papers in the introductory Chapter summarize the positions of Drs. Glenn Suter (EPA) and Jim Wilson (Resources for the Future) regarding whether the use of often-expensive risk assessments in developing countries can be justified, given evolving regulatory institutions and limited resources.