Given the broad (economic, social and environmental) objectives of a green economy, and the limitations associated with mainstream measures of economic performance (such as gross domestic product), an alternative or expanded set of indicators is required for measuring progress toward a green economy. This article develops a composite index for measuring green economic performance, based on 26 indicators across the economic, social and environmental dimensions. The index will enable comparison of a country's green economic performance both over time and relative to other countries. Furthermore, the index is constructed in such a way as to allow for disaggregation (i.e. for scores on individual components to be seen at a glance), such that areas of specific concern can be easily identified and addressed, and progress in each area monitored over time. The index was tested on data from 193 countries, and the resulting country rankings were assessed.