The Zona Reservada del Alto Purús is a 2.7 million-ha wilderness area, larger than the country of Belize, located in Peru’s Amazonian lowlands. Bounded by Manu National Park to the south and a mix of Brazilian indigenous territories and protected areas to the north and east, this sprawling, untouched backcountry is one of the most remote and poorly explored regions of Peru. Four major Amazonian rivers – the Madeira, Purús, Juruá, and Ucayali – have their start here in the low hills of the Fitzcarrald Arch, where hyperdiverse plant and animal communities remain almost entirely intact, and nomadic, uncontacted indigenous populations crisscross vast expanses of unsettled forest. But as logging teams attracted by its abundant mahogany make their way deeper into the region, the future of its biological and cultural diversity is increasingly in doubt. This book is an introduction to the Alto Purús region, written by a team of 40 biologists, conservationists, geographers, and sociologists who know it first-hand. It provides an overview of what is currently known about the area’s plant, fish, amphibian, reptile, bird, and mammal communities; its physical landscape; land use along its borders; its settled and uncontacted indigenous populations; and impacts from hunting and logging, drawing on the authors’ recent field work as well as on dozens of earlier reports and expeditions. As the book brings to light the surprising amount of research carried out to date in this inaccessible area, it also underlines how much remains to be learned. Throughout the volume, the authors emphasize the strategic importance of the Alto Purús region for the protection of uncontacted indigenous groups and for the large-scale conservation of the Amazonian flora and fauna. Because the Alto Purús is currently under study by the Peruvian government with a view to establishing a conservation area, the book concludes with a chapter of practical recommendations for categorization and zoning. We argue that the establishment of a well-designed national park in the region, linking highelevation Andean communities in adjacent Manu National Park with protected forest in Brazil and creating the largest complex of strictly-protected area in the Amazon basin, will benefit biodiversity, uncontacted groups, and the settled communities outside its borders.