The library's collection focuses on topics of culture and history, literature and language, folklore and regional studies of German settlement areas in East-Central and Southeastern Europe (Greece, Croatia, Republic of Moldova, Romania, Serbia, Slovakia, Slovenia, Ukraine and Hungary). The collection comprises about 20,000 books and 1,000 periodicals. It also contains DVDs, CDs and micro-materials with a focus on Southeastern Europe. A special feature is the microfilm collection of rare German-language periodicals from Southeastern Europe.

The holdings can be borrowed or used in the reading room. Copying facilities and Wi-Fi access are also available. Media items can be researched in the IKGS OPAC and ordered on site or in advance. Since 2016, the library has run a national and international interlibrary loan service. Consultation on subject-specific topics is also offered. 

The archive of the IKGS documents the influence and works of numerous writers, publicists and scientists from Central and Southeastern Europe, especially from Romania, Hungary and Germany. The main focus of the archive is the 20th and 21st centuries. It contains pre-mortem bequests and posthumous estates as well as collections of materials and photo archives on Southeastern European history and literature. Some archive holdings have already been indexed online in Kalliope and can be viewed there.