The specter of information is haunting sciences. With these words, Wojciech H. Zurek invited fellow scientists to attend the 1989 Santa Fe Institute workshop on which this proceedings volume is based. Thermodynamics, statistical mechanics, the quantum theory of measurement, the physics of computation, dynamical systems, molecular biology, and computer science-information remains central to the 32 essays collected in this new edition of Complexity, Entropy & the Physics of Information. Like the original meeting, this two-volume reprint explores the connections between quantum and classical physics, information and its transfer, computation, and their significance for the formulation of physical theories. A newly written introduction from attendee Seth Lloyd contextualizes the significance of this record of a meeting that marked the intersection of information, physics, complexity, and computation.