Special collections are, next to authors’ libraries, the salt of every large library. For example, the acquisition of the collector’s library of Badenhop in 1961 laid the foundation for the twentieth century, and the library of Marlinger deepened our collection of war-time literature and literature from the front. Specific collections for the Chamisso Prize, of anecdotes or haikus, as well as collections of specimen copies have singularly added greater density and diversity to the library’s holdings. The filling of gaps, ad hoc and systematically, is a constant task of acquisition. Equally important is the current and retrospective documentation of literary trends on at least a representative scale: this remains true for alternative and underground literature, for poetry slams and for smaller literary journals, for graphic novels, press proofs and art books with a literary first printing. Developing the library »gradually to a collection of sources and materials, unique in its scope and completeness« was the goal of the first archivist at Marbach in 1902 and remains its challenge in the twenty-first century.