This collection of new papers surveys the major themes in the study of information, including mechanisms for implementing desired social allocations. The volume is a review of current debates and state of the subject and is intended as a reference for graduate students of economic theory, particularly of general equilibrium. The contributors relate their own work to that of Leo Hurwicz, whose contributions established the field of information and allocation rules. They are as J.O. Ledyard, X. Calsamiglia, T.A. Marschak, J.S. Jordan, K.R. Mount, K.J. Arrow, J.J. Laffont, E. Maskin, J.C. Rochet, A. Mas-Colell, R.B. Wilson, M. Aoki, J. Green, A. Postlethwaite, D. Schmeidler, J. Roberts, W. Thomson. This volume should prove to be a useful reference in many graduate courses on economic theory, and could be the required text in an advanced course on theoretical microeconomics and general equilibrium. It should also be useful for economists and information scientists.