The Institute of Historical Research library is a collection of published primary sources, reference works and bibliographies for the history of Western Europe and its colonial expansion. More than half of its holdings are in languages other than English, with the Romance languages particularly well represented. The library's collections of bibliographies and archival guides are of particular value for researchers preparing to undertake research abroad. Material can be found using the electronic catalogue, by browsing the open shelves or through the library’s excellent collection guides, which are listed by subject or region.

The library’s French History collections are extensive and cover a chronological range from late antiquity to the present day. The 18th and 19th centuries, including the Revolutionary period, are well represented, with particular strengths in holdings of political and legal works. Coverage of French local and regional history in all periods is uniquely rich, and supplemented by excellent periodical holdings in this area. The Colonial History collection contains significant holdings on French activity in Africa, the Caribbean and North America, as well as French sources for the history of Canada (some printed prior to 1800). The Low Countries History also contains a large amount of material in French.

The Spanish History collection is a significant and highly regarded resource covering Spain and its colonial history. Holdings for the territories of the Spanish Empire and their subsequent history are particularly well represented, and complemented by material in the Caribbean History, Latin American History and Mexican History collections. There is also strong coverage for the 20th century, in particular the Spanish Civil War. A highlight of the collection is the extensive range of sources for the local and regional history of Spain, many of which are unique in the UK. Holdings on Catalonia (many in Catalan) are also strong. Researchers working on specific periods may also find useful material in the Italian History and Low Countries History collections.

Coluccio Salutati
Francesco Novatio ed., 'Epistolario di Coluccio Salutati' (1911)

The Italian History collection offers good general coverage of the history of Italy from the early MIddle Ages to the present day, and is particularly strong for the period before 1494. There are excellent holdings of edited sources, as well as a large selection of library and archival guides. General history works are particularly strong for Venice, Tuscany and Rome, and there are extensive sets of source material and reference works. The collection also includes a small number of early printed works.

While relatively small in size, the Portuguese History collection is among the most significant of its kind in the UK. It contains particularly strong selections of sources for late medieval and early modern Portugal. Portuguese language sources for the history of Lusophone countries can also be found in the Latin American History collection, which contains a significant subsection on Brazil, and in the Africa collection.

Romance language material can also be found in a number of the library's other collections, including Colonial History (mainly in French and Spanish), Military History (particularly accounts of the World Wars) and General History (reference works, history of European universities, travel writing).