Abstract : In France, the first Institutional Repositories (IRs) were set up in 2002, using the E-Prints software. At the same time, a centralized repository was organized by CNRS, a French multidisciplinary research institute, for the deposit of all French research output. In 2006, most of the French scientific and scholarly research organisations signed a “Protocol of Agreement” to collaborate in the development of this national archive, HAL. Independently, the Ifremer Research Institute launched its own IR (Archimer) in 2005. We have compared the development of HAL and Archimer. Our results show that Ifremer's policy of self-archiving has resulted in 80% of its research output being made Open Access (OA). In the same time interval, HAL, lacking a self-archiving mandate, had only 10% of its target research output deposited. Ifremer's specific implementation of its mandate (a staff dedicated to self-archiving) is probably not affordable for most French research institutions but its self-archiving mandate itself is, and Arthur Sale's comparative studies in Australia have shown that the essential element is the mandate itself. The European Universities Association, mindful of the benefits of mandating OA, has recommended self-archiving mandates for its 791 universities. Self-archiving mandates have already been adopted by 22 universities and research institutions worldwide (including Harvard, Southampton, CERN, and one CNRS research laboratory) as well as 22 research funding agencies (including NIH, ERC, & RCUK). OA maximizes research usage and impact. It is time for each of the universities and research institutions of France to adopt their own OA self-archiving mandates.