The author examines the notion of National Art Library. He recalls to mind the history of the Library of the Victoria and Albert Museum, which had in previous times an inward looking attitude, because it was regarded as predominantly a museum department. At the beginning of the eighties only, was undertaken a reflection on the missions of a « National » Library of Art. But there is no precise and definitive definition and the concept of Specialized National Library is difficult to determine. Beyond the usual missions of any national library, the author proposes the notion of « leader ».