The growing human population and a shift to more resource-intensive habits and behaviors are increasing the demands on global ecosystems. Natural capital is a way to describe Earth’s natural assets, including soil, air, water, and living things, existing as complex ecosystems, which provide a range of services to humans. Depleting and degrading these reserves may irreversibly reduce the availability of benefits to future generations. This In-Depth Report presents an overview of ideas, debates, and progress so far in natural capital accounting, in particular in accounting for ecosystems and their services.