The main objective of this paper is to attempt to indicate in what way concepts such as modelling, simulation, optimization, etc. can be applied as a tool in the design of policies for socio-eoonomie development. A model as a basis for the design of policies should be in accordance with the existing administralive~ statistical 7 political and sociological infrastructures. The objectives of the development should be reflected by the model. Both the frequent unavailability of data of good quality, as well as the fact thai policy and decision makers should have some insight in the siruclure of the model, ask for the application of simple methods. As an illustration of the oonsideralions as laid down in this paper, two case studies are presented.