This Special Paper includes 29 papers presented at several meetings of the International Geoscience Programme (IGCP) Project 497: “The Rheic Ocean: Its origin, evolution and correlatives.” The Rheic Ocean was one of the dominant oceans of the Paleozoic. Its origin can be traced to the Avalonian-Cadomian orogenies in the Latest Neoproterozoic. Closure of the Rheic Ocean began in the Lower Devonian and ended with the assembly of the supercontinent Pangaea. Its history involves North and South America, Africa, Baltica, and a number of peri-Gondwanan terranes. Papers mirror the history of the Rheic Ocean and document a chain of global events and produced orogenic belts that extend discontinuously from México to easternmost Europe. The ocean’s evolution was responsible for the formation of a wide variety of sedimentary basins; it significantly impacted the history of life, and it profoundly influenced contemporary paleoclimate and global environmental conditions. Fields of research involved in its study range widely and, as this book illustrates, include stratigraphy, sedimentology, paleontology, paleogeography, paleooceanography, igneous and metamorphic petrology, tectonics, structural geology, provenance analysis, geochemistry, geochronology, and paleomagnetism. Despite decades of research, aspects of the evolution of the Rheic Ocean remain controversial. With this book, the authors hope to answer a number of important questions and to encourage further research.