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 at the University of California, Berke­ ley, his former post-doctoral fellows at Bell Laboratories, and his published coauthors. We express our sincere apology to any potential authors who fit these categories and whom we may have unintentionally failed to approach. Our job as editors of the Review of Economic Design Radner issues turned out to be easy, thanks to the enthusiastic response we received from authors and the quality of their submissions.