From the website:

"The Dorot Jewish Division is responsible for administering, developing and promoting the exploitation of one of the world’s great collections of Hebraica and Judaica. Reference and research services are available in a dedicated Jewish studies reading room on the first floor of the Library’s landmark Stephen A. Schwarzman Building.

Primary source materials are especially rich in the following areas: Jews in the United States, especially in New York in the age of immigration; Yiddish theater; Jews in the land of Israel, through 1948; Jews in early modern Europe, especially Jewish-Gentile relations; Christian Hebraism; antisemitism; and world Jewish newspapers and periodicals of the nineteenth and twentieth centuries."

Consult the NYPL library catalogue here. See also the Digital Yiddish Sources page on this website for several online collections of the Dorot Jewish Division.