The music collection of the research library has grown historically and is important for Thuringian music history. The collection contains theorical writings on music, 1,400 of which are handwritten, and encompasses 8,000 scores. In addition, it contains compositions by the 17th and 18th-century conductors of the Gotha court orchestra, written in their own hand.
The collection also includes compositions by Georg Anton Benda (1722–1795), who worked as court conductor and composer of church cantatas, masses and passion music at the Gotha court from 1750 to 1788.
130 manuscripts and old prints document the work of the Bach family of composers, whose members maintained numerous contacts in Gotha. These include, for example, a copy of the Credo in unum Deum (BWV 232/13) from Johann Sebastian Bach's B minor Mass written by his pupil Johann Friedrich Agricola (1720–1774) or eight piano sonatas by Johann Christoph Friedrich Bach (1732–1795) from Bückeburg, which have survived in Gotha.
The collection arose from different sources, including the musical records of the ducal house of Saxe-Gotha and a group of vocal works from around 1800 by Johann Michael Bach the Younger (1745–1820).
The collection thus includes works from the 17th to the 20th century that were intended for different contexts and composed in various genres, such as church and funeral music, courtly entertainment or sacred and secular songs.