The ducal library was founded in the residenz town of Wolfenbüttel by Duke Julius of Brunswick-Lüneburg (1528–1589), who began collecting books around 1550 while studying in France.
[2] In the period 1570–1572, the libraries of the monasteries of Dorstadt, Wöltingerode, Heiningen and Steterburg were, in the course of the introduction of the Reformation in the duchy, transferred to Wolfenbüttel.
As early as 1571, the Duke had entrusted the church musician Leonhart Schröter with library administration duties.
He expanded it to include the estate of the theologian Matthias Flacius and the collections of the Georgenberg monasteries near Goslar, Brunshausen and Hamersleben.
However, in 1618, just a few years after his accession, the succeeding Duke Friedrich Ulrich handed over the entire collection, which now comprised around 5,000 manuscripts and prints, to the Helmstedt University Library .