The Rare Book & Special Collections Reading Room of the Library of Congress holds a small number of rare books of Slovenian interest or origin.

The oldest rare book in the collection related to Slovenia is the Croatian translation of Abecedarium by Primus Truber (1508-1586), a Slovenian Protestant reformer who penned the first two Slovenian printed books, Abecedarium and Catechismus. The translation from 1561 Tabla za dicu [Board for children] is printed in Glagolitic characters and has been digitized by the Library.

From the 18th century the Library holds a number of interesting books including two titles by Giovanni Antonio Scopoli (1723-1788), the "Linnaeus of the Austrian Empire." Scopoli was an Italian naturalist and doctor who spent time in regions that are now part of Slovenia where he gathered specimens of insects and plants. His books Entomologia Carniolica and Flora Carniolica are well-known for their accurate descriptions and for being the first to identify a number of species. Also concerning Carniola is the 1788 volume by the father of Slovenian historiography Anton Tomaž Linhart (1756-1795) Versuch einer Geschichte von Krain und der übrigen südlichen Slaven Oesterreichs [Attempt at a history of Carniola and the remaining southern Slavs of Austria]. The Library of Congress has only the first volume of this work in the original edition.

An early title for the study of the Slovene language is the grammar of Mihael Zagajšek (Georg Sellenko) (1739-1827) Slovennska grammatika oder Georg Sellenko's Wendische Sprachlehre in deutsch und wendischen Vortrag [Slovene grammar or Georg Sellenko's Wendish language text in German and Wendish speech], remembered for being the first grammar to use Slovene (and not just German) language for the text, which run in parallel on opposite pages. Published in 1825 in Laibach (Ljubljana) is another rare grammar of Slovene, that of Franc Serafin Metelko (1789-1860) Lehrgebäude der slowenischen Sprache im Königreiche Illyrien und in den benachbarten Provinzen [Slovenian textbook for the Kingdom of Illyria and the neighboring provinces] which introduced what is called the Metelko alphabet. Although Metelko's phonetic alphabet was not adopted, it remains a curiosity in the history of the codification of the Slovene language.

A landmark work of interest to all of the South Slavic nations is the original 1601 printing of Il regno degli Slavi hoggi corrottamente detti schiauoni [Realm of the Slavs] by Mauro Orbini (1550-1611), a Benedictine monk from Dubrovnik (Ragusa). Although Orbini incorporated unsubstantiated legends and chronicles, his history of the Slavs, with a special focus on the South Slavs, also relied on many other sources including works by Orthodox and Protestant writers which were banned by the Vatican, resulting in his work being banned as well in 1603.

Also in the Library of Congress Rare Book collection is the 1722 Russian translation of Orbini's history Knīga Istorīograḟīi︠a︡ pochatīi︠a︡ imene, slavy, i razshīrenīi︠a︡ naroda slavi︠a︡nskogo [Book of historiography on the origins of the name, glory and expansion of the Slavic people], translated by Sava Vladislavić (1669-1738), a diplomat from Herzegovina and Dubrovnik who served on behalf of the Russian tsar Peter the Great. Il regno degli Slavi and its Russian translation were of enormous significance for the historiography of the South Slavs and the Pan-Slavic philosophy.

Unrelated to the history of Slovenia, but of considerable importance to the history of the United States is the contribution by prominent Slovenian Bishop Frederic Baraga (1797-1868) who, as a missionary among the American Indians and a trained linguist, wrote a grammar of the Chippewa language, A theoretical and practical grammar of the Otchipwe language (Detroit, 1850).

From the 20th century the Library of Congress holds several translations into Slovenian such as Stanko Leben's of Don Quixote from 1935 which was donated by the bibliophile and Cervantes collector Leonard Kebler, and two translations of novels by Bernard Malamud donated by his wife Ann Malamud. In the Third Reich collection are two books about Slovenia that formerly belonged to Adolph Hitler as well as 10 Nazi party posters from World War II. All materials held by the Rare Book and Special Collections Reading Room must be used onsite, unless there happens to be a digitized version on the Library of Congress website.