Dela 21 • 2004 • 27-40 URBAN GEOGRAPHY AND COMPLEXITY Denise Pumain University Paris Panthéon-Sorbonne, 13 rue du Four, 75 006 Paris, France e-mail: pumain@parisgeo.cnrs.fr Abstract The contemporary approach of complex systems raises common questions that could be handled by a transdisciplinary theory. We demonstrate how the main concepts of urban geography could be integrated in such a theory ofcomplexity. We illustrate the complexity approach by a short presentationof the SIMPOP model that uses a multi-agents formalism for the simulationof the evolutionary properties of systems of cities. Key words: system of cities, urban geography, complex system, complexity