The densely populated Campi Flegrei resurgent caldera is one of the widest known, best studied and highly dangerous volcanoes of the world. This monograph will synthesize the current knowledge of this volcano, through different review chapters. The book consists of about 15 chapters, each on a specific aspect, authored by well-recognized experts. The volume attempts to cross the barriers between the volcanological, geological, geochemical and geophysical perspectives, with the aim of offering a comprehensive and up-to-date reference to earth-science scholars, as well as land planners and civil defence officers. The articles will cover the following general topics: -Geological and geophysical structure of the caldera -Magmatic and hydrothermal systems: architecture and dynamics -Caldera current state, monitoring and modelling -Volcanic and related hazards assessment -Urban inhabitation, present urbanization and geology.