The Convention on the protection and promotion of the diversity of cultural expressions was adopted by UNESCO in November 2005. It allows the notion of cultural diversity to assume the shape of a legal instrument and an international treaty. The text of the Convention is examined here in comparison with the Declaration of principles (October, 2001). It focuses specifically on semantic discussions and relationships with other international instruments. These reveal the points of dispute between States and the implicit stakes which require an evaluation of the gains and losses of the different actors involved (private sector, public sector and civil society). The legitimacy and viability of the Convention are then analyzed in the light of the perspectives for implementation and follow-up. Developments which occur in other international arenas are also considered, as cultural diversity seems to « spill over » the agenda of the action lines of the World Summit on Information Society (WSIS) and the World Intellectual Property Organization (WIPO).