* ''Ozar Yisrael'' (principal editor, 1906–1913, 10 volumes) (אנציקלופדיה אוצר ישראל), an encyclopedia concerning all matters of [[Jews]] and [[Judaism]]. It has the distinction of being the first comprehensive (not exclusively on Jewish topics) [[encyclopedia]] in the [[Hebrew language]]. Eisenstein undertook this work in response to perceived limitations of the [[English language]] Jewish Encyclopedia (Levy 2002).
For obvious reasons, he was known by many colleagues as "Ba'al ha-Otzarot" ("Master of the Ozars"). Although Eisenstein was a scholar of extraordinarily broad learning, he remained staunchly orthodox his political views were being marked by hostility toward [[Reform Judaism|Reform]] and [[Conservative Judaism]] (Sherman, 1996).
