ABSTRACT: The Group on Earth Observations Biodiversity Observation Network (GEO BON) was established to promote and provide guidance toward a global observation network on biodiversity and ecosystems for decision makers and the scientific community. Here we comment on three key challenges in the development and implementation of monitoring schemes and indicators of ecosystem services (ES): (1) combining ES observations, data and methods across scales; (2) identifying operational ES metrics that consider the interactions between people and ecosystems; and (3) integrating the diversity of socio-cultural values and knowledge into monitoring activities. We discuss these challenges with the goal to stimulate the ES research community to help tackle these focus areas in ES monitoring.