his paper reviews 9ome practical aspects of using results from a long range transport model of sulfur in Europe in a policy analysis context. This context is provided by the IIASA RAINS (Regional Acidification Information and Simulation) model which is used for analyzing international strategies to control acidification in Europe over a 1980–2030 time horizon (Alcamo et al. 1984; Hordijk et al. 1985). The RAINS model consists of several linked submodels (Figure 1), one which is a source-receptor matrix based on the so-called EMEP model of long range transport of sulfur in Europe* (Eliassen and Saltbones, 1983). Submodels which describe NO emissions and deposition are presently being added to the RAINS system. In the interim, sulfur is assumed to be the principal long term contributor to acidification of Europe’s environment.