We are pleased to help celebrate Roy Radner's 75th birthday, by issuing in one volume the papers that originally appeared in his honor in two special issues of Review of Economic Design (Vol. 6/2 and 6/3-4, 2001). Through his truly original ideas and lucid writing, Roy has influenced and guided the theory community for decades. Many colleagues and students have found their own work shaped and improved by Roy's wide-ranging curiosity, his encouragement, and his keen insights. In soliciting contributions to the Review of Economic Design Radner issues, we decided to approach his former students...