Preface: Denise Pumain.- Introduction: Celine Rozenblat, Guy Melancon.- I: Concepts and visualizations of multilevel spatial networks.- 1: Celine Rozenblat, Guy Melancon: A small world perspective on Urban Systems.- 2: Jean-Francois Gleyze: Topological clustering for geographical networks.- 3: Alain L'Hostis : Theoretical models of Time-space: the role of transport networks in the shrinking and shrivelling of geographical space.- II: Tools for networks analysis: 4.- Guy Melancon, Celine Rozenblat: Structural analysis of networks.- 5: Antoine Lambert, Romain Bourqui, David Auber: Graph Visualization for Geography.- 6: Pierre-Yves Koenig : Exploring hierarchies using the DAGMap.- III: Empirical studies of spatial multilevel networks: 7: Cesar Ducruet: Port in a world maritime system: a multi-level analysis.- 8: Celine Rozenblat, Guy Melancon, Romain Bourqui, David Auber : Comparing multi-level clustering methods on weighted graphs: the case of worldwide air passengers traffic 2000-2004.- 9: Charles Bohan, Berengere Gautier: Multilevel analysis of Corporations Networks: a comparison between agro-food and automobile strategies for urban development.- 10: Marie-Noelle Comin: The Capture and diffusion of knowledge Spillovers: the influence of the position of Cities in a network.- 11: Patrice Tissandier, Tien Phan-Quang, Daniel Archambault: Defining polycentric Urban Areas through commuting cohesion in France.- Conclusion: Celine Rozenblat, Guy Melancon.