RUBINSTEIN, ISAAC (1880–1945), rabbi, leader of Mizrachi and of Polish Jewry. Born in Dotnuva, Lithuania, Rubinstein was ordained a rabbi and also graduated from the faculty of law at Moscow University. He officiated as a rabbi in Genichesk, Ukraine (from 1906) and from 1910 was the government-appointed rabbi of Vilna. In 1919 he was elected to the Vilna rabbinate by the Orthodox, and in 1929 was elected as a Zionist and Mizrachi representative. From the date of his arrival in Vilna, Rubinstein engaged in activities in all spheres of Jewish life, especially during World War i, when he remained in Vilna and became one of the leading representatives of Vilna Jewry vis-à-vis the various occupying powers. During the Lithuanian regime in Vilna (1920), he was minister of Jewish affairs, and when Vilna returned to Polish rule he continued to be officially recognized as one of the heads of the community. From 1922 to 1939, he was a member of the Polish senate. He defended Jewish rights vigorously and his speeches made a great impression on Polish government circles. At the same time he was a leading member of Mizrachi and active in various capacities in the World Zionist Organization. After the 21st Zionist Congress (1939), he returned to Poland and remained with the community during the initial period of German and Soviet occupation. He made his way to the United States in 1941 and continued his work on behalf of Polish Jewry. He taught at the Yeshiva University in New York until his death.
S. Kerstein, in: Jewish Outlook, 5 (March, 1941), 8–9; A. Werner, in: The New Palestine, 32 (April 24, 1942), 12; J. Cohen, Vilna (Eng., 1943), index; H. Abramovich, Farshvundene Geshtaltn (1958), 163–70.