The Gotha Research Library preserves a remarkable collection of 525 medieval manuscripts. It is mainly composed of pieces seized during the Thirty Years' War or acquired by the Ernestine ducal house of Saxe-Gotha-Altenburg (1640–1825) or the ducal library (1825–1918). The medieval manuscripts, which are heterogeneous in terms of content and provenance, primarily reflect the bibliophilic and scholarly interests of the ducal house of Gotha, which until the end of the 18th century was the largest and politically most powerful of the princely houses of the Ernestine dynasty. They also bear witness to the pronounced collecting interests of the Gotha librarians in the first half of the 20th century. In a first step, 247 medieval manuscripts from the library's entire holdings will be digitized. The in-depth indexing has been funded by the German Research Foundation or carried out by the library itself according to standards.