Investigations of ecosystem services have journeyed from discussing how people depend on nature, through refining definitions and classification schemes, to accounting for multiple benefits that nature provides for people in decision-making processes. Ecological and economic approaches are becoming increasingly integrated in ecosystem service studies, and a common language is emerging. In particular, landscape-ecological and welfare-economic approaches are often utilized and integrated in these studies. Ecosystem services extend the traditional conservation agenda, offering a fuller consideration of the benefits and costs arising from land-use changes and marine spatial planning. It has also been argued, however, that ecosystem services distract from the original mission of biodiversity conservation. The citations included in this article include foundational works; overviews and assessments; definitions and classification schemes; debates; and applications in terrestrial, freshwater, and marine ecosystems.