The superfamily Chalcidoidea (the jewel wasps) are part of the insect order Hymenoptera. The superfamily comprises more than 27,000 known species, with an estimated total diversity of more than 500,000 species, meaning that the vast majority have yet to be discovered and described. Most of the species are parasitoids, attacking the egg, larval stage or pupal stage of their host, though many other life cycles are known including gall associates and fig pollinators. This landmark volume has been co-authored by world authorities on the systematics and biology of chalcidoid wasps. It provides an introduction to the superfamily, a review of chalcidoid morphology, an overview of the fossil record, a phylogenetic framework for the revised classification of the superfamily, an identification key for the 50 recognized families, and detailed treatments of the individual families. For many years to come this important book will serve the needs of hymenopterists and professional entomologists, taxonomists and systematists, entomologists working on parasitic wasps as biological control agents, and ecologists working on parasite-host interactions.