Abstract : The French research institutions have recently signed a memorandum of understanding for the joint deployment of open archives based on the HAL platform (Hyper Articles on Line) developed by CCSD-CNRS. This unprecedented commitment pools all universities and Grandes Ecoles through their respective Conferences, and research organizations like CNRS, Inserm, INRA, INRIA, CEMAGREF, CIRAD, IRD and Institut Pasteur, and represents almost all researchers and academics in the French government sector. Some other public research organisations CEA, INERIS, INRETS and IFREMER recently joined the movement. This decision to take on a common platform for depositing and valorizing scientific output comes as a result from a far-reaching process started up in 2000 when the CNRS founded its Center for Direct Scientific Communication (Centre pour la Communication Scientifique Directe) with the aim like arXiv to provide scientists with the capacity to disseminate freely their scientific output. The HAL service was launched in 2001. Additionally, CNRS by committing themselves to the international Open Access movement backed the Max Planck Gesellschaft in the Berlin Declaration signed in October 2003. The Berlin Declaration has been signed by over 160 institutions now – including a great many Italian universities! – and is considered the starting point of institutional commitment to Open Access. In March 2005, in a joint press release, the four largest French research institutions (CNRS, INRA, INRIA, Inserm) announced their agreement to develop interconnected institutional open access repositories. This decision provided ground to the HAL platform that became the repository supported by national-level research institutions. At the time, the platform was moving towards a repository collecting both doctoral dissertations and scientific papers in a wide range of fields, thereby providing various subject communities with specific deposit and retrieval interfaces. The national agreement that has been recently signed now brings another significant challenge to the fore: the need to set up technical and organizational rules for circulating formatted data flows between the organizations' internal information systems and the HAL platform. This is the only means to make the platform a reliable tool for the valorization of French scientific output. This challenge is all the more real as HAL is the French member of European DRIVER project aimed at interconnecting Europe's institutional repositories.