Belgium has been an active contributing member of RISM since its inception.
Out of the 100,000 records described in A/I series Einzeldrucke vor 1800 (Individual Prints before 1800), there are around 8,000 Belgian records, while for the A/II series Music Manuscripts there are a little more than 35,000 out of the 850,000 listed in the collective database (as of May 2014).
The vast majority of Belgian records were created between 1993 and 1998 when - thanks to the financial support of Belgian Federal Government - a team of musicologists was created associating three research institutions, the Royal Library of Belgium, the Brussels University and the Katholieke Universiteit Leuven. All the music manuscripts pertaining to RISM A/II and preserved at the Royal Library of Belgium and the Brussels Conservatory were described and encoded, as well as some sources of particular importance held by other institutions in Flanders and in Wallonia, for a total of more than 26,000 records.
Nowadays, the RISM working group in Belgium has two offices:
the Brussels office, located at the Music Division of the Royal Library of Belgium, which deals with the Royal Library musical sources and contributes musicological expertise to the Coordinating Committee of the RISM Advisory Council; and
the Mechelen office, located at Cemper - Centrum voor Muziek- en Podiumerfgoed, a non-profit association financially supported by the Flemish regional government that aims to find, describe and preserve the Flemish musical heritage in Flanders.