There have been systematic attempts over the last twenty-five years to explore the implications of decision making with incomplete information and to model an economic man as an information-processing organism. These efforts are associated with the work of Roy Radner, who joins other analysts in this collection to offer accessible overviews of the existing literature on topics such as Walrasian equilibrium with incomplete markets, rational expectations equilibrium, learning, Markovian games, dynamic game-theoretic models of organization, and experimental work on mechanism selection. Some essays also take up relatively new themes related to bounded rationality, complexity of decisions, and economic survival. The collection overall introduces models that add to the toolbox of economists, expand the boundaries of economic analysis, and enrich our understanding of the inefficiencies and complexities of organizational design in the presence of uncertainty.