In 1917, at age twenty-four, he become rabbi of The Temple in Cleveland, Ohio, one of the nation's largest, best known Reform congregations where he served for forty-six years. Abba Hillel Silver was an early champion of rights for labor, for worker's compensation and civil liberties, though his highest priorities were to advance respect for and support of Zionism. He was to do this first among Reform Jewish congregations, then by American Jewry, then by the American public and politicians, and last by the international community—the United Nations in particular. Silver was one of the chief Zionist spokesmen before the United Nations in the Palestine hearings of 1947.
A nationally-known orator and author of many scholarly works, he also served as head of many Jewish and Zionist organizations.