The Environmental Performance Index (EPI) is a new and strongly performance-oriented composite index. It builds on the Pilot Environmental Performance Index that was published in 2002 and is designed to be a powerful supplement to the environmental targets set forth in the U.N. Millennium Development Goals. The EPI measures progress toward a set of targets of desirable environmental outcomes, taking into account a country's current policies. It is anticipated to be of particular value to decision makers because of its strict input-output framework and short- to medium-term time horizon, which promotes accountability and performance evaluation at the policy level.

Like the Environmental Sustainability Index (ESI), the EPI permits cross-country peer-reviews to identify best practices, leaders, and laggards, but it primarily tracks performance changes over time with respect to clearly identified, achievable targets. These targets are based on existing international agreements, scientific evidence on the harmful impacts of pollution on humans and ecosystems, and economically feasible environmental protection strategies. The 2006 Pilot EPI was formally released in Davos, Switzerland, at the Annual Meeting of the World Economic Forum on Thursday, 26 January 2006.