The collections of the University of Illinois Library in the various fields relating to Medieval Studies are strong across the board. Its bibliographical resources include, in addition to an extensive collection of topical and serial print bibliographies, the online International Medieval Bibliography; Mirabile: Digital Archives for Medieval Culture (Medioevo Latino); and Iter: The Bibliography of Medieval and Renaissance Europe from 1400-1700. For a fuller listing, see Internet Medieval Studies Resources. The Library's collections of print and electronic scholarly journals are also extensive, including full runs of many rare older periodicals as well as current periodicals in all areas of Medieval Studies.

In addition to its vast open stacks collections housing millions of volumes, the Library has several specialized libraries overseen by specialist subject librarians, including Architecture & Art; Classics; Literatures & Languages; History & Philosophy; Music & Performing Arts; and Rare Books & Manuscripts.

The Ricker Library of Architecture & Art is a comprehensive art historical library and includes an extensive collection of facsimiles of illuminated medieval manuscripts, with particular strengths in fifteenth-century Europe. Online resources include the Princeton Index of Christian Art. For a fuller listing, see Visual Arts: Medieval Studies Library Resources.

The Classics Library, built upon the collections of Wilhelm Dittenberger and Johannes Vahlen, two prominent nineteenth-century German classicists, is especially strong in Greek and Latin authors, Greek and Latin grammar, philology, epigraphy, papyrology, and manuscript facsimiles. Medieval Latin, patristics, and Byzantine and Modern Greek are also well represented. It has superb collections of primary sources in both print and electronic form, including the Latin text series  Bibliotheca Teubneriana, Poetria Nova, Monumenta Germaniae Historica, Patrologia Latina, Acta Sanctorum, Corpus Christianorum, and Corpus Scriptorum Ecclesiasticorum Latinorum, as well as a comprehensive collection of editions of individual texts by medieval Latin authors. The collections in Byzantine Studies are second only to those at Dumbarton Oaks.

The History & Philosophy Library has very strong collections in medieval political, social, economic, and ecclesiastical history. Major online databases include Medieval and Early Modern Sources Online. For a fuller listing, see History: Medieval Studies Library Resources and Philosophy and Religion: Medieval Studies Library Resources.

The Literatures & Languages Library has excellent holdings in the medieval vernacular languages and literatures, particularly in medieval English, Germanic, and Romance languages, but also in Celtic. In addition to comprehensive monograph and serial collections, the Library has extensive microform and digital resources such as, in medieval English, British Literary Manuscripts, the Dictionary of Old English Corpus, Anglo-Saxon Manuscripts in Microfiche Facsimile, the Middle English Compendium and Chaucer Bibliography Online. For a fuller listing, see Literaturs & Languages: Medieval Studies Library Resources.

The Music & Performing Arts Library is one of the finest in the United States, ranking with those at Harvard, Yale, Berkeley and Princeton. A special strength is the Renaissance Archives microfilm collection, which includes all major late medieval music manuscripts. For a fuller listing, see Music: Medieval Studies Library Resources.

The Rare Book & Manuscript Library has one of the great incunable collections in North America, as well as a substantial collection of medieval manuscripts, including illuminated manuscripts such as the deluxe Capetian Coronation Book. Complementing the manuscript holdings is an extensive collection of manuscript facsimiles. For a partial listing, see Facsimiles of Medieval & Renaissance Illuminated Manuscripts.

The Renaissance Archives: Musicological Archives for Renaissance Manuscript Studies, 1400-1600