Mediatized by the Millennium Assessment (MA ) in 2005, the notion of ecosystem services (ES) has become recently the main reference for international environmental policies (broadly, including forestry policies, agri-environmental measures, conservation policies...). ore than 1300 authors were involved in the MA and participated to the production of an international agri-environmental norm: ecosystem services. Some firms's representatives were also involved in the MA . The interest of multinational corporations for environmental issues is not new, the private sector, understood here as the business, contributes for a long time to the formulation of international norms and policies, at the national level with national governments and also in participating in committees of international organizations. If any part of the literature in International Relations and International Political Economy focuses on the role of firms in the international environmental governance, it does so primarily in terms of firms influence in the production of international policies (Falkner 2008, Levy and Newell 2005). These approaches, both heuristic as they are, do not consider the participation of firms such as the mobilization of brokers which are able to diffuse some policy instruments and norms as to invite policy transfer studies (PTS ) (Delpeuch 2009; Dolowitz and Marsh 2001). From the analysis of the gray literature of the WBCSD (world business council on sustainable evelopment) and a series of interviews with key players in the process of the Millennium ecosystem assessment (MA ) (some representatives of the firms, of international organizations and of scientific community), we will show that transnational networks composed of representatives of science and firms have formed and / or strengthened at the MA , and thus promoted the circulation of the concept of ecosystem services among many "worlds". We will show in particular that the firms' representatives have evolved the notion a