First of all, this book is intended to give the reader a simple introduction to the Urban Decision Room (UDR) system in definitions and diagrams. Second, it demonstrates the model-based construction of the system in terms of urban planning. Third, it focuses on the planning methodological function of the system in design and decision-making activities which occur in the process of urban development. The UDR should be placed in the tradition of urban planning design and planning discipline that is taught, and into which research is carried out, at the Faculty of Architecture at the Delft University of Technology. The UDR was developed at the faculty as one of the new design and planning methods with its own specific features.