Brief Description: Correspondence with approximately 1,350 individuals and organizations. Family correspondence. Letters from individuals including S. An-Ski, Baal Makhshoves, Hayyim Nahman Bialik, Nathan Birnbaum, Ber Borochov, Jacob Dinesohn, Saul Ginsburg, Jacob Glatstein, Peretz Hirschbein, David Ignatoff, Joseph Jaffe, David Kessler, Judah L. Magnes, Golda Meirson, Nahum Baruch Minkoff, Shmuel Niger, Moshe Olgin, Joseph Opatoshu, Isaac Leib Peretz, Abraham Reisen, Joseph Schlossberg, Sholem Aleichem, Mordecai Spector, Nachman Syrkin, Baruch Vladeck, Chaim Weizmann, Hillel Zeitlin, Zerubavel, Chaim Zhitlowsky. Correspondence with Yiddish organizations. Correspondence with the Jewish National Workers Alliance, 1916-1942, including the main office and branches in the U.S. and Canada as well as with its affiliated Yiddish schools. Correspondence with the Poalei Zion party in the United States and Canada, 1914-1947; Palestine, 1924-1937; Poland, 1936. Correspondence of the party's press organs, *Der yidisher arbeiter*, 1923-1926; *Yidisher kemfer*, 1931-1933; and *Di tsayt*, 1921-1922. Letters from affiliated organizations such as Hehalutz, Pioneer Women, League for Labor Palestine. Manuscripts of novels, plays, poems, essays, and articles. Personal documents and photographs.