One of the challenges in crafting environmental policy is determining how to measure a policy's effectiveness. The Environmental Performance Index (EPI) aims to help simplify this process by analyzing and organizing data to "provide a gauge at a national scale of how close countries are to established environmental policy goals." Here, interested readers will currently find the EPI's most recent report (released in 2018), which quantitatively "scores 180 countries on 24 performance indicators across ten issue categories covering environmental health and ecosystem vitality." This report, written in accessible language, includes an introduction, a brief explanation of their methodology, a summary of their results, and sections addressing each of the ten issue categories in greater depth, as well as an executive summary for policymakers. Readers may also be interested in the categorical lens (found under the results menu), which provides concise explanations of the EPI's issue categories and corresponding performance indicators. Those interested in accessing the report's data and the specifics of its methodology will find these in the downloads section. The EPI is produced jointly by the Yale Center for Environmental Law & Policy and Columbia University's Earth Institute, in collaboration with the World Economic Forum. New EPI reports are released biennially in even-numbered years.