Fueled by advances in information technology, data-driven decisionmaking has transformed every corner of society, from business to biology. In the policy domain, quantitative performance metrics have reshaped decisionmaking processes in many arenas, including economics, health care, and education. The 2008 Environmental Performance Index (EPI) brings a similar datadriven, fact-based empirical approach to environmental protection and global sustainability. The EPI focuses on two overarching environmental objectives: reducing environmental stresses to human health; and promoting ecosystem vitality and sound natural resource management.