The collection contains at present more than 150.000 titles, registered in the online catalogue. Most of these refer to sheet music and literature published before 1900, the so-called historical collection. Furthermore the library contains a collection of musicological literature, performing editions and microfiches which may be consulted in the reading room. A part of the collection is lendable.
The library consists of more than 120.000 titles of sheet music of which ca. 40.000 titles belong to the historical collection, printed before 1900.
Besides rare first editions of works of for example J.S. Bach and A. Corelli, the collections contain a number of important manuscripts, among which the Siena Lute Manuscript, Mozart's Galimathias Musicum KV 32 and the so-called Frankenberg Autograph of J.G. Walther.
Over the years several important collections have been added to the library, like those of the Théâtre Français de La Haye (700 scores with parts, printed before 1850) and of the Royal Court Orchestra (150 titles).
In some collections historical and modern editions are mixed: the Alsbach collection (11.000 titles), the collection of harp music of Phia Berghout (1000 titles) the Frans Vester collection of flute music (4000 titles), and the Willem Noske collection of violin music (27.000 titles). The NMI has also taken in the historical collection of military music (ca. 3500 titles), given on loan by the Ministry of Defence.
In large part these and other historical collections can be consulted through microfiches and facsimile editions in the study room.
Historical sources and journals
This collection contains over 10.000 titles, among them original and rare editions of 16th and 17th Century treatises of music theorists like Gaffurius, Virdung, Mersenne and Praetorius. Notable are also the collections of dance books and historical methods for various instruments. Besides, the Institute owns numerous 18th and 19th Century journals (350 titles).
In large part these collections are searchable through the library catalogue. The historical library collection has been registered in STCN (Dutch national bibliography up till 1800) and in the International Inventory of Musical Sources RISM.
Reference works secondary literature
Reference works and secondary literature are available for the following research areas: general history of music, history of musical life in the Netherlands, historical performance practice, history of repertoire, (historical) musical instruments, history of music printing, historical dance and composers' biographies.