The proposed research project is an outgrowth of an initial collaborative effort to review and assess the state of knowledge in the fields of decision and risk analysis, with the aim of providing a perspective for future research directions in these disciplines. A recent review of the evolution and state of the fields suggests four broad and significant trends: (1) increased focus on decision and risk analysis applications, (2) more interdisciplinary research among normative and descriptive researchers in direct and allied disciplines, (3) growing efforts to reexamine existing theory, and (4) accelerated growth of interactive, intelligent software for decision support and training. Consistent with these broad research trends, this proposed research project is divided into the following two categories: (1) Theory and methodological development and (2) risk analysis and management. Theory and methodological issues to be addressed include model formulation, modeling uncertainty, modeling preferences, and optimization. A fundamental premise in the proposed work is that usually, more information is acquired than is necessary to reach an optimal choice. Moreover, as precise inputs from individuals are generally unreliable, imprecise information may be more relevant, appropriate, and all that is required to arrive at a rational decision. Given this premise, the investigators shall reexamine the existing theory and build and test (both computationally and behaviorally) interactive, integrated, intelligent decision support models to facilitate model building, uncertainty and preference assessment, and optimization consistent with this premise. The results of the research should provide new normative and descriptive knowledge regarding human inference and decision making capabilities and behavior, new methodologies, and intelligent, interactive software to support decision making training and practice. This research will be carried out in collaboration with Professor Derek W. Bunn of the London Business School. It is the objective of the U.S.-United Kingdom Cooperative Science Program to promote mutually beneficial research cooperation and to enable U.S. scientists to take advantage of special research opportunities. This award fulfills that objective by enabling Dr. Herbert Moskowitz to spend three years in collaboration with British scientists with complementary expertise.