PART I. Cellular Aspects: 1. Elementary Cellular Processes Driven by Actin Assembly, Lamellipodia and Filopodia. J. Victor Small and Klemens Rottner.- 2. Coupling Membrane Dynamics to Actin Polymerization. Shiro Suetsugu and Tadaomi Takenawa.- 3. Endocytic Control of Actin-Based Motility. Andrea Disanza et al.- 4. Actin in Clathrin-mediated endocytosis. Marko Kaksonen.- 5. Actin Cytoskeleton and the Dynamics of the Immunological Synapse. Viveka Mayya and Michael Dustin.- 6. Actin-Based Motile Processes in Tumor Cell invasion. Matthew Oser et al.- 7. Actin-Based Chromosome Movements in Cell Division. Rong Li.- 8. Roles for Actin Dynamics in Cell Movements During Development. Minna Roh-Johnson et al.- PART II. Molecular Aspects: 9. Regulation of the Cytoplasmic Actin Monomer Pool in Actin-Based Motility. Pekka Lappalainen et al.- 10. From Molecules to Movement : In vitro Reconstitution of Self-Organized Actin-Based motile Processes. Marie-France Carlier and Dominique Pantaloni.- 11. The WASP-Homology 2 Domain and Cytoskeleton Assembly. Roberto Dominguez.- 12. Formin-mediated Actin Assembly. David Kovar.- 13. Visualization of Individual Actin Filament Assembly. Emmanuèle Helfer.- 14. Movement of Cargo in Bacterial Cytoplasm : Bacterial Actin Dynamics Drives Plasmid Segregation.- PART III. Physical Aspects: 15. Protrusive Forces Generated by Dendritic Actin Networks During Cell Crawling. Ovijit Chaudhuri and Daniel A. Fletcher.- 16. Mathematical and Physical Modeling of Actin Dynamics in Motile Cells. Anders E. Carlsson and Alex Mogilner.- 17. Force Production by Actin Assembly : Simplified Experimental Systems for a Thorough Modeling. Cécile Sykes et al.