Conducted during the spring of 2004 on the eastern side of the Peruvian Andes, this inventory offers biological and social analyses of the Zona Reservada Megantoni. The participating scientists survey three of the most inaecessible and isolated sites in this rugged territory, examining vascular plants, dung beetles, fishes, reptiles and amphibians, birds, and large mammals. The report also features a brief history of the Megantoni region and its peoples, reviewing more than ten years of collaborative work between scientists and the native communities in the area, including the Machiguenga, Ashaninka, Yine Yami, and Nanti peoples. The report concludes with recommendations for the region's conservation and management, calling for the protection of 216,005 hectares as Santuario Nacional Megantoni. Such a measure would keep intact a corridor between two of the largest protected areas in Peru, the Parque Nacional Manu and the conservation complex in Cordillera Vilcabamba.