Mahler was born on August 15, 1899, in
Nowy Sącz,
Galicia,
Austria-Hungary, the son of a scholarly and business family. He attended the Nowy Sącz municipal public school, where he was the only Jewish student, went to the Nowy Sącz yeshiva, and studied with private tutors. Mahler left the yeshiva when he was fifteen and finished his secondary education in
Kraków. He then went to
Vienna, where he studied history and philosophy at the
University of Vienna and the Talmud at the rabbinical assembly. He received his doctorate in 1922, with his dissertation on the sociological problems of progress. He then returned to Poland, where he taught history in Jewish secondary schools, participated in the
Left Poale Zion, and promoted modern Jewish historical research. He and
Emanuel Ringelblum founded the Jewish Young Historians Circle, which was later affiliated with
YIVO's Historical Section. He was actively involved with YIVO as a researcher and editor. From 1924 to 1937, Mahler taught general and Jewish history in the Gymnasium and the Lyceum "Ascola" in
Warsaw. He was active in the Warsaw branch of the
Polish Historical Society. He identified with the Jewish workers' movement since his youth. He contributed to and edited
Der Yunger Historikes from 1926 to 1929,
Bleter far Geshicte from 1934 to 1939, the YIVO yearbooks,
Der Virtshaftliche Lebn, and
Fraie Yungt. He also headed the Jewish Workers Educational Society in Poland (Geselshaft Ovent Kursn far Arbeter) until 1931, when the Polish government dissolved it. In 1937, Mahler immigrated to America at the invitation of YIVO and settled in
New York City. He worked as a lecturer in YIVO's research student courses, the
Jewish National Labor Alliance's teachers seminary, and the
Workmen's Circle's teachers courses. He was also a lecturer of the Herzliah Hebrew Teachers' Institute from 1938 to 1939, and in
World War II he taught Jewish history at the Jefferson School for Social Studies and the School of Jewish Studies. Mahler died in
Ramat Gan on October 4, 1977. == References ==