The National Library of Israel, where the International Institute for Jewish Genealogy is located, is a major genealogical resource in itself. Its origins going back to 1892, the Library is today the largest repository of Judaica in the world, with extraordinary and often unique treasures in print, manuscript, microfilm and voice-recorded form.

Genealogists are aided by having an abundance of reference works and genealogical collections under one roof, including biographical studies, family and community histories, rabbinical encyclopedias and "responsa", "Yizkor books", population records, newspapers, maps, art works and a host of other basic materials in Hebrew, Yiddish, Ladino and every other language of the Jewish world.

Specifically genealogical collections include the Paul Jacobi Library and Papers (described separately), the Dan Bar-Lev Collection and a group of books on the antecedents of various Jewish families in Denmark and Scandinavia generally. In addition, the Library houses the private archives and correspondence of over 400 scholars, writers, artists and thinkers, including those of Ahad Ha-Am, Shai Agnon, Walter Benjamin, Martin Buber, Albert Einstein, Gershom Scholem and Stefan Sweig, together with the Sassoon Family Archive. Beyond that, it preserves thousands of Hebrew manuscripts, frequently accompanied by a colophon containing valuable genealogical information. To these must be added the over 47,000 Hebrew manuscripts (and over 200,000 fragments) on microfilm, another potential genealogical resource. Within these categories, some 2,000 ketubbot (marriage contracts), replete with family information, has been digitalized from the Library's own collection, together with many hundreds more from other sources. In addition there are, for example, a group of over 600 original pinkassim (registers) of communities, hevrot (associations) and mohelim (circumcisers). And this is not to mention the digitalization of six early Hebrew newspapers from the 19th and 20th centuries (Halevanon, Hamaggid, Havazelet, Hazefirah, Hamelitz and Hazvi/Haor/Hashkafa). In brief, the Library is an ever-growing treasure-trove for genealogical research.