Conducted during August of 2003 in the broad interfluvium between the Amazon and Putumayo rivers in the vast lowlands of northeastern Peru, this inventory provides both biological and social analyses of the region, with concrete recommendations for its protection. Collaborating with the 26 indigenous communities who have led the initiative to conserve this intact, terra firme forest north of the Amazon, participating scientists examined the upper headwaters of the Yaguas, Ampiyacu, and Apayacu rivers. This report covers surveys of vascular plants, fishes, reptiles and amphibians, birds, large mammals, and bats. The recommendations call for protection of 1.9 million hectares in a complex that includes three Communal Reserves surrounding a core area of strict protection — Yaguas National Park.