The Environmental Sustainability Index (ESI) benchmarks the ability of nations to protect the environment over the next several decades. It does so by integrating 76 data sets ¡tracking natural resource endowments, past and present pollution levels, environmental management efforts, and a society's capacity to improve its environmental performance ¡ into 21 indicators of environmental sustainability. These indicators permit comparison across thefollowing five fundamental components of sustainability: Environmental Systems; Environmental Stresses; Human Vulnerability to Environmental Stresses; Societal Capacity to Respond to Environmental Challenges; and Global Stewardship. The issues reflected in the indicators and the underlying variables were chosen through anextensive review of the environmental literature, assessment of available data, rigorous analysis, and broad-based consultation with policymakers, scientists, and indicator experts. The ESI provides a powerful environmentaldecisionmaking tool tracking national environmental performance and facilitating comparative policy analysis. It enables a more data-driven and empirical approach to policymaking.