In the domain of desertification and climate change an important amount of new knowledge and research material has been obtained from the many projects carried out in the EU-DG12 Environment and Climate programme. However, so far little effort has gone into making this scientific material available as part of practical planning or management tools for regional public policy makers. In this presentation, we will dwell on the experiences gathered in developing a generic spatial Decision Support System for integrated environmental policy-making at the regional level. The experiences are taken from a two year EC-project, MODULUS. In this project models and scientific material from 4 past EU-projects are integrated that represent the climatological, physical, economic and social aspects of land degradation and desertification in the Northern Mediterranean. The individual models operate at very different temporal and geographical scales. At the most detailed temporal scale, processes taking few minutes are represented, and, at the most detailed geographical scale dynamic models running on top of raster-GIS layers are implemented. The MODULUS DSS is developed as a very interactive, transparent and (geo)graphical instrument. It runs on PC machines under Windows NT and makes extensive use of Active X and component technology. In order to demonstrate its generic applicability the MODULUS DSS is applied to two case regions: the Argolid (Greece) and the Marina Baixa (Spain). In the presentation we will dwell on the practical and scientific lessons learned from the project, and more in particular on the difficulties involved in adapting scientific material to the needs of integrated policy-making.