This document was written to provide technical information regarding theecological importance of the National Petroleum Reserve – Alaska (NPR–A).Several scientists from various organizations and with diverse areas of expertisecame together to produce this report. In this technical report, we first summarize the NPR-Abackground, including the history of its formation and current land management, as well as a description of the physical and biological features contained within the NPR-A. We then provide technical information about several groups of sensitive species that rely on the NPR-A: caribou, Arctic fishes, shorebirds and loons, tundra vegetation, wolverines, moose, and polar bears. Next, we provide information about the importance and history of Indigenous science and lifeways within the NPR-A. We finish with informationabout the landscape value of the NPR-A when considering ecosystem intactness, wildness, soil carbon storage, and terrestrial ecosystem representation. This report by no means includes an exhaustive covering of the values foundin the NPR-A to both humans and non-humans, yet provides technical information based on our many years of expertise and experience working in this critical area of the Arctic.