Allen Newell is most often described as one of the founders of artificial intelligence, but he could equally well be described as a founder of cognitive science, the field of human-computer interaction, or the systematic study of computational architectures. The symposium held at Carnegie Mellon University in his honor paid tribute to the breadth of his career with contributions from top scientists in all these disciplines. Their papers are included in this volume, along with commentaries about the implications of the presentations for Soar, a computational architecture for intelligent action to whose design Allen devoted the last decade of his life. The volume therefore forms a remarkable snapshot of science in the style that Allen inspired, simultaneously striving for integrative coherence in theory building while accounting for a wide range of detailed empirical data in cognitive and computer science.