A megadiverse county, Costa Rica is known globally for its success in reversing deforestation and pursuing a growth model based on the sustainable use of its environmental resources. However, energy use and related greenhouse gas emissions increased in the last decade. Private cars are a major and growing source of emissions affecting climate and air quality. Waste disposal still relies on landfills, and much wastewater is untreated. Costa Rica's extensive protected area network and pioneering programme of payments for ecosystem services have helped reduce biodiversity loss and extend forests' carbon sequestration capacity. However, more should be done to tackle pressures on biodiversity from development of infrastructure and settlements, tourism, farming and fishing. The sheer scale of investment needed to achieve the Sustainable Development Goals calls for improving the efficiency of public spending, mobilising private finance, strictly enforcing regulations and providing adequate incentives. This is the first OECD Environmental Performance Review of Costa Rica. It evaluates the country's progress towards sustainable development, with a special chapter focusing on biodiversity, and provides 52 recommendations.