Within the French 'Margins' Programme (Groupement de Recherches 'Marges', or 'GDR Marges'), The Gulf of Lions was selected as a key area where scientists specialized in complementary aspects of geosciences (structural geology, tectonics, stratigraphy, sedimentology, various aspects of modeling) work together in order to better understand the processes that control the formation and evolution of continental margins. A key objective was to link offshore data (that mainly consist of seismic data and few wells) and onshore studies (mainly based on well and field data). This special edition of Marine and Petroleum Geology on the Gulf of Lions presents some of the main results obtained during three years of research by the group 'GDR Marges-Golfe du Lion'.