IIASA's model of Acid Rain is an interactive set of submodels with graphical output. The model has been developed in collabration with UN Economic Commission for Europe and in the context of the Geneva Convention on Long Range Transboundary Air Pollution. The model covers 5 compartments of which up to now 3 have been implemented as submodels. the models output include maps of Europe showing isolines of sulphur deposition and areas with a soil pH below a certain level which can be chosen by the user.