(The prayer-book was later more thoroughly revised after his death.) In his own congregation his influence effected consolidation and growth; in the Jewish community he participated in the formation and reorganization of societies. In 1876 Jastrow fell severely ill, and for some years his public activities were limited by his poor health, which necessitated a sojourn in the south of Europe. During this period of withdrawal he fully matured the plans for his great work, "A Dictionary of the Targumim, the Talmud Babli and Yerushalmi, and the Midrashic Literature" (London and New York, 1886–1903). When the dictionary was approaching completion in manuscript (1895), the Jewish Publication Society of America was about to begin work on its projected new translation of the Bible into English, and to Jastrow was entrusted the chief-editorship. At the time of his death the translation of more than half the books of the Bible had been revised by him. In addition to these two great undertakings, he was a member of the Publication Committee of the Jewish Publication Society from the time of its establishment, and was connected with the "Jewish Encyclopedia" as editor of the department of the Talmud; he took a prominent part in the proceedings of the Jewish Ministers' Association, held a seat in the central board of the Alliance Israélite Universelle at Paris, was on the committee of the Meḳiẓe Nirdamim, was one of the vice-presidents of the American Federation of Zionists, and was active in relieving the needs, material and intellectual, of the Russian immigrants. Jastrow initially allowed his congregation to join the Reform Union of American Hebrew Congregations. After the Reform movement united around the radical "Pittsburgh Platform" in 1885, Jastrow, along with many other rabbis of the time, withdrew his congregation's membership. In 1886 together with Rabbi Henry Pereira Mendes (founder of the Orthodox Union) he helped Rabbi Sabato Morais establish the Jewish Theological Seminary of America. It was only in 1913, ten years after Jastrow's death, that the next generation of management altered the Orthodox principles of the school, and from them emerged Conservative Judaism. He was removed by his congregation in September 1892 in favor of the Reform ordained Dr. Henry Berkowitz. Jastrow attributed this decision to the growing popularity of radical reforms and the congregation's desire to compete for membership with the more liberal synagogues.