This page focuses on the English language, and covers some major collections in the United Kingdom and Ireland.
COPAC is the unified catalog of UK and Irish academic, national, and specialist libraries, but the rare books collections may not always be integrated into collective catalogs like these. Similarly, WorldCat may or may not list all of the older materials held in various libraries, but it may provide a helpful first indication of where your materials can be found.
If you're not sure what you're looking for, perusing printed bibliographies may be a good place to start. The British Library has exhaustively cataloged its own collections for decades. Browsing some of its many catalogs might be a good option. More information on searching for texts can be found on the home page of this guide.
Searching online catalogs is the fastest way to find what you're looking for if you already know what it is. If you want to explore, browsing bibliographies may be the way to go. Many paper bibliographies are available under Z call numbers at both Regenstein and Crerar libraries, and in facsimile editions via Google Books and Hathi Trust. More information on bibliographies can be found on the home page of this guide.
The British Library has exhaustively cataloged the books in its collections. Some of these catalogs are listed below. The catalogs by Pollard and Redgrave (covering books printed 1475-1640) and Wing (covering books printed 1641-1700) are classics, listing the majority of all books printed in English through 1700. Below you will find some specific catalogs by genre, by region, or by topic, and some early bibliographies.
The British Library has vast collections of incunabula and early printed books. The national libraries of Scotland, Ireland, and Wales focus on collections of books relating to their cultural areas, but hold important early collections as well.
When requesting access to old and rare materials, most institutions will require that you apply for some sort of researcher's card and may require to see some evidence of why you need to use the materials. It is a good idea to anticipate this, and familiarize yourself with the requirements at the libraries you intend to visit before you travel. It is also advisable to bring an original letter from your department chair or dissertation advisor attesting to your research needs.
More information on visiting libraries and archives can be found on the home page of this guide.
The UK and Ireland are home to some of the oldest and most important academic libraries in the world. A few of the most significant collections are listed here, but there are many more.
For libraries in North America with collections of early printed books, please see the Collections in North America page of this guide.
As was the case with all European languages, English orthography was unstable in the early modern period. As D. G. Scragg points out in A History of English Spelling, the mercantile background of many early printers, as opposed to the highly trained medieval scribes, initially led to more diversity of spelling. William Caxton, the first printer in England, spent much of his life in the Low Countries and brought some Dutch spelling conventions with him--the h in ghost is attributed to his enduring influence. More information can be found on the home page of this guide, and in the following volumes.