This chapter claims that sustainable development is an ethical statement, on a par with human rights. Based on Our Common Future, the authors derive three equally important moral imperatives: satisfying human needs, ensuring social justice, and respecting environmental limits. They develop a normative model for sustainable development by linking the imperatives to six themes, selecting indicators and assigning thresholds that must be met. The authors argue that the themes can come neither from short-term political consensus nor from parochial stakeholder preferences. Rather, they must come from the moral imperatives of sustainable development and from theories fundamental to understanding those imperatives. The chapter uses data for 117 countries and applies a cluster analysis to illustrate how different groups of countries face different challenges. Meeting one threshold may make it harder to meet another, and the analysis focuses on identifying countries that have managed to reconcile these trade-offs in a good way.