During the 70 years of its existence, the IES has collected rich and nationally important archival materials, comprising about 500 files of historical and 200 files of current documents.
List of more important funds:
- Carinthian plebiscite 1920
- Archives of the Office for the Occupied Territories, Ljubljana, 1918-1921
- Archives of the Inter-Allies plebiscite commission, Section SCS, 1920
- Archives of the District Office of Borovlje/Ferlach, 1919-1920
- Archives of the Peace Conference Commission with the National Government of the SCS in Ljubljana, 1918-1920
- The Mačkovšek Archives
- Archives of the National Council of Velikovec/Völkermarkt
- Paris Peace Conference 1947
- Ivan Rozman's Archives
- Dr. J. Vilfan's Archives
- Archives of the dr. Justa Pertota
- Archives of theAndreja Gabrščka
- Archives of the G. Golia
- Pariška konferenca 1919
- Dr. J. Goričar's Archives
- Documents on fascist oppression, 1918-1941
- Scientific Institute with the SNLC Archives, 1941-1945
- Archives of the Scientific Institute - Department for Border Issues, 1945–1948
- IES Archives, the Slovene Littoral Region Department
- Archives of the Lava Čermelja