One of the crucial issues in specifying requirements for an In formation System is to guarantee the effectiveness and the efficiency of their future implementation. The objectives of the methodology, proposed in the IDA project and presented in this paper, have been: 1. To propose a model and an associated language for a more rigourous specification of Information Systems, 2. To develop among others two complementary software tools allowing the experimental evaluation of this specification, by prototyping and simulation, before to implement it · and, more recently, 3. To outline an automated monitoring of the implemented Information System.