In 1980, a group of scientists from national laboratories, universities, and other research organizations gathered informally in a series of meetings to consider the state of research on risks to health, safety, and the environment. Each scientist had conducted research on the subject. All felt that the traditional disciplines and professional societies to which they belonged were neither ade quate nor appropriate for addressing the extraordinarily complex problems of assessing the risks inherent in modern society. The con sensus of the group was that a new society was needed to address these problems in a scientific and objective way. From these initial meetings, the Society for Risk Analysis was formed The major aims of the Society for Risk Analysis, as stated in its constitution, are • to promote knowledge and understanding of risk analysis techniques and their applications; • to promote communication and interaction among those engaged in risk analysis; and • to disseminate risk analysis information and promote the advancement of all aspects of risk analysis. Members of the Society are drawn from a variety of disciplines, including the health sciences, engineering, the physical sciences, the humanities, and the behavioral and social sciences. An import ant function of the Society is the annual meeting, at which var ious aspects of risk analysis are discussed. The first annual meet ing, represented by this volume, was the International Workshop on the Analysis of Actual vs.