This analysis of the information contained in the 2004 IUCN Red List of Threatened Species provides an insight into the status and trends of the world’s species of plants and animals, with a focus on those at greatest risk of extinction. The publication highlights the taxonomic groups and species that are at the greatest risk of extinction; recent documented extinctions; trends in the status of threatened species, including the new Red List Index; regions of the world where threatened species tend to be found; the threats that are driving species towards extinction; the social and economic context in which extinctions are taking place; and the conservation responses that are available. This in depth analysis is the first major publication by the Red List Consortium, a group of organizations comprising IUCN (in particular the Species Survival Commission), BirdLife International, Conservation International (in particular the Center for Applied Biodiversity Science), and NatureServe.