The main points and the main conclusions of a workshop held June 27–30 1983 at Interlaken, Switzerland, are reported. There was general agreement among the participants that ideal simulation, providing unambiguous information about the behaviour of the first wall material, is at present out of reach. In this situation the route to follow is to use the existing simulation facilities in a concerted effort to understand the damage accumulation processes and thereby create the background for prediction or appropriate simulation of the behaviour of the first wall material.