What is a 'sustainable nation' and how can we identify and rank 'sustainable nations'? Are nations producing and consuming in a sustainable way? Aggregate indicators have been proposed to answer these questions. This paper quantitatively compares three aggregate indicators of sustainability: the World Bank's 'Genuine Savings' measure, the 'Ecological Footprint' and the 'Environmental Sustainability Index'. It is concluded that rankings of sustainable nations vary significantly among these indicators. Implications of this disagreement for analysis and policy are suggested.