The International conference on Design & Decision Support Systems in Architecture and Urban Planning is organised bi-annually by the Eindhoven University of Technology. This volume contains a selection of papers from the seventh conference that was held at De Ruwenberg Castle in Sint-Michiels Gestel, The Netherlands, from 2 to 5 July, 2004.Traditionally, the DDSS conferences aim to be a platform for both starting and experienced researchers who focus on the development and application of computer support in the areas of urban planning and architectural design. This results in an interesting mix of well-established research projects and first explorations. It also leads to a very valuable cross-over of theories, methods, and technologies for support systems in the two different areas, architecture and urban planning. This volume contains 22 peer reviewed papers from this year's conference that are organised into five sections:* Applications of Artificial Intelligence,* Visualisation fro Design and Decision Support,* Simulation and Agent Technology,* Design Research and Design Support Systems,* Geographical Information Systems.Together, these papers provide an excellent overview of the latest results in research and development of design and decision support systems in architecture and urban planning.