The 2020 Environmental Performance Index (EPI) provides a data-driven summary of the state of sustainability around the world. Using 32 performance indicators across 11 issue categories, the EPI ranks 180 countries on environmental health and ecosystem vitality. These indicators provide a gauge at a national scale of how close countries are to established environmental policy targets. The EPI offers a scorecard that highlights leaders and laggards in environmental performance and provides practical guidance for countries that aspire to move toward a sustainable future. The metrics on which the 2020 rankings are based come from a variety of sources and represent the most recent published data, often from 2017 or 2018. Thus the analysis does not reflect recent developments, including the dramatic drop in air pollution in 2020 in the wake of the COVID-19 pandemic or the greenhouse gas emissions from the extensive Amazonian fires in 2019. These indicators provide a way to spot problems, set targets, track trends, understand outcomes, and identify best policy practices. Good data and factbased analysis can also help government officials refine their policy agendas, facilitate communications with key stakeholders, and maximize the return on environmental investments. The EPI offers a powerful policy tool in support of efforts to meet the targets of the UN Sustainable Development Goals and to move society toward a sustainable future. Overall EPI rankings indicate which countries are best addressing the environmental challenges that every nation faces. Going beyond the aggregate scores and drilling down into the data to analyze performance by issue category, policy objective, peer group, and country offers even greater value for policymakers. This granular view and comparative perspective can assist in understanding the determinants of environmental progress and in refining policy choices.