In each of these fields, the key facets of the concept of ``agent'' appear to be goal, state, behaviour, heterogeneity. The collaborations already undertaken between members of ModelAge make us believe that a common model may be found. To ensure precision, the model will be described mathematically. The many formalisms used in each field could then be grounded in this common semantic framework, allowing an integrated multi-formalism approach. This approach would result in large savings for the development of information systems requiring multidisciplinary techniques, which are acquiring an ever-increasing importance.