Composite indicators are synthetic indices that are used to rank country performances in specific policy areas. Many do, however, suffer from methodological difficulties. Specific difficulties linked to indices for environmental sustainability are analyzed through the illustration of several sets. The most critical issues are linked with a poor analytical framework and a lack of common unit for the aggregation. Some measure directly the state of the environment while other use proxies such as pressure or response indicators or even a mix of these. A new composite index for environmental sustainability was developed in the EU project EPSILON, which aimed at assessing European regional sustainability for policy decision making related to the improvement of regional sustainability. Indicators are expressed according to a coherent framework issuing from the ‘driving force–pressure–state–impact–response’ approach with an innovative weighting scheme derived from human health impact assessment based on disability adjusted life years (DALYs). Results are compared with a more conventional aggregation technique based on an equal weighting coupled to various normalization techniques. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/60990/1/376_ftp.pdf