The development cooperation system is undergoing a dramatic process of change. New actors are on stage, new instruments (beyond ODA) are being used, and the fields of work have been clearly widened. The enlargement of the development cooperation system is in line with the ambitious and comprehensive 2030 Agenda. However, those changes also imply massive tensions and challenges to the current development cooperation system in terms of its objectives, procedures and narrative. This paper presents some of these challenges in light of the “leaving no-one behind” mandate. The paper discusses, firstly, how the development cooperation system can be brought up to date, taking into account massive changes in the international landscape; secondly, it argues why development cooperation may be still useful and effective in supporting an Agenda that goes beyond ODA; and finally, it discusses some dilemmas around the way in which resources should be allocated in order to preserve the distributive purpose of development cooperation.