Among the many German institutions that participated in carrying out the National Socialist plunder of books, the Reichssicherheitshauptamt (RSHA) took the leading role. In order to provide their department for Research on Ideological Opponents with source material, the Security Service of the SS, in collaboration with the Gestapo, seized Jewish private and public libraries all over Europe and transferred them to their Berlin headquarters. The result was the so-called “Judenbibliothek”, a library built exclusively of looted Jewish books. Starting in 1941, Jewish forced laborers were used to sort and catalog the stolen books. These groups of conscripted scholars became known as “Grumach-Gruppe” and “Talmudhundertschaft”. Drawing on private correspondence of two surviving forced laborers, Jenny Wilde (1874–1949) and Ernst Grumach (1902–1967), this article illuminates the victims’ perspectives: How did they perceive the task they were forced to do? What did they hope for? However, to gain an accurate understanding of the forced laborers’ experience, our picture of the “Judenbibliothek”, the context that frames this experience, has to be corrected first. Based on provenance marks of books that were incorporated into the “Judenbibliothek” of the RSHA, this article offers a more detailed picture of the “Judenbibliothek” than previous studies. It discusses classification scheme, processing practice, retrieval and usage of the books, and challenges the widely held notion, that the librarians of the Security Service never succeeded in transforming the heap of hastily accumulated books into a working library of immense proportions.