International audience Geneviève Thibault de Chambure (1902-1975), musicologist specialized in French chanson and instrumental music from 1450 till 1550, collector of rare scores and musical instruments, curator of the Instruments Museum of the Paris Conservatory from 1962 till 1973, founder of a team of specialists in organology and musical iconography supported by the CNRS, is also known to posterity as the founder of the Société de Musique d'Autrefois. Between 1927 and 1932 and between 1952 and 1975, two annual concerts were organised under her presidency, one of religious music, the other of secular music. The programmes covered four centuries of "early" music and enabled a select audience, in Paris but also in the regions and even abroad, to discover these repertoires performed on historical instruments collected by G. Thibault, nowadays all in the Museum of Music. Starting from these collections of rares manuscripts and prints, preserved since 1980 in the National Library of France (Music Department), the successive conductors of the SMA (Roger Désormières, Pierre Chaillé, Antoine Geoffroy Dechaume) were able to prepare most of the used materials. The author, after having portrayed the history of the SMA, describes briefly the fifty archive boxes now preserved in the Museum of Music and which, besides an abundant correspondence and a complete collection of the Society's programs, also contain the orchestral materials used for the concerts that are not yet catalogued. Problems that may occur in conservation and analysing are discussed, as well as several aspects of cataloguing, research and utilization.