World Guide to Special Libraries is the most comprehensive directory of libraries specializing in specific subjects worldwide. The completely revised and updated 11th edition lists over 30,000 libraries under approx. 800 subject headings. Amongst others, these include major central libraries, faculty and institute libraries, school libraries, corporate and administrative libraries, as well as special libraries in the traditional sense of the word and general libraries with major specialized holdings.

For national libraries acting as deposit libraries for all national publications of a country, a specialization as mentioned above is not given. However, due to their great importance for scientific work and subject related research they are listed as an extra chapter.

Besides contact details, entries typically include information regarding inter-library lending, library director or head of library, book, periodical and manuscript holdings statistics, special holdings, areas of collection and much more. The index at the end of the work lists all libraries alphabetically by name.