The collection contains play manuscripts, programs, playbills, posters, photographs, correspondence, agreements, scrapbooks, clippings, printed ephemera, and memorabilia relating to Yiddish theater primarily in the early twentieth century, especially the interwar period. Also included are items of printed ephemera related to Yiddish film, Hebrew theater, and a broad range of Jewish performers, including cantors, singers and dancers. Geographically, the materials originate predominantly in Poland and other parts of Eastern Europe, including parts of the Russian Empire and, later, the Soviet Union; and, to a lesser extent, the United States, especially New York City. Also included are materials from Western Europe, Palestine (Eretz Israel), South America, and other regions around the world. Among the theater personalities represented in the collection with significant amounts of material are Herz Grossbard, David Herman, Joseph Winogradoff, Rudolf Zaslavsky, Zygmunt Turkow, Jonas Turkow, Moyshe Lipman, Ida Kaminska, and Esther Rachel Kaminska. The theater groups best represented include the Varshever Yidisher Kunst-Teater (VYKT; Warsaw Yiddish Art Theater), founded by Zygmunt Turkow and Ida Kaminska; the Vilna Troupe; Yung Teater / Nay Teater (Warsaw; Vilna), under the direction of Michael Weichert; the Moscow State Yiddish Theater (known by its Russian acronym "GOSET"); Maurice Schwartz's Yiddish Art Theatre, of New York; and the Hebrew theater "Habimah." A wide variety of other professional as well as amateur theater groups are represented with smaller amounts of material.

This collection contains correspondence between Mendel Osherowitch and many important literary and political figures, as well as Yiddish manuscripts by Osherowitch, clippings, photos, and obituaries and letters written to his family after his death. These materials illustrate Osherowitch’s importance in the Yiddish literary field as well as his role in various Jewish organizations.