Does the challenge of sustainable development (SD) have implications for our approches to decision-making and evaluation? Do we need specific Sustainability Assessment Models (SAMs) and if so; what are the options? In this article, interpretations of SD are discussed as well as the role of democracy in relation to decision-making at the societal level. Taking democracy seriously means that individuals are regarded as Political Economic Persons and organizations as Political Economic Organizations. Among approaches to decision-making, Positional Analysis, PA, is advocated as being compatible with normal imperatives of democracy and useful for Sustainability Assessment purposes. PA belongs to the disaggregated, ideologically open category. The article ends with a note on the relationships between ex ante and ex post evaluation. Are the same models useful or do we need other methods for ex post evaluation?