The Cambridge Companion to Aquinas, edited by Eleonore Stump and her friend and former teacher Norman Kretzmann († 1998), appeared almost thirty years ago. In the time since the publication of that volume, an enormous amount of research on Aquinas’s thought has appeared. The time is right, then, for a redoing of that Companion volume. But because so much time has elapsed since the first Companion volume appeared, it was not feasible just to revise it and reissue it as a second edition. Instead, it was necessary to start over completely. With the exception of Eleonore Stump, all the contributors to The New Cambridge Companion to Aquinas are new and have written original papers for this volume; and even Stump’s paper in the first Companion volume has been replaced by an entirely fresh essay.