The Cordillera Escalera mountain range on the Loreto-San Martín border in Amazonian Peru was barely known to scientists until the September 2013 expedition described in this report. Richly illustrated with twenty four color plates featuring more than one hundred photographs, this volume contains the full results of the expedition’s rapid inventories of the geology, plants, fishes, amphibians, reptiles, birds, and mammals in the Cordillera Escalera, as well as in-depth descriptions of the history, daily life, and natural resource use of local Shawi communities. Contributors also discuss threats to and opportunities for the landscape and its people and offer recommendations for sustaining biodiversity and human well-being in this megadiverse region of Peru. This volume contains the expedition team’s full report in both Spanish and English, as well as an overview in Shawi.