In the preface to this work, Jastrow sharply criticized those linguistic and etymological scholars who claimed that obscure terms in Talmudic literature are primarily derived from Koine Greek.

Jastrow held that Greek influence on Jewish Babylonian Aramaic was minimal, and that most obscure terms could be much more simply traced to Hebrew origins.

Although it was controversial at the time, delivering a sermon in Polish does not violate any Orthodox Jewish restriction, nor does following a funeral procession on foot on the Sabbat.

[3] Broken in health, Jastrow, with his family, spent the spring and summer of 1862 in Breslau, Berlin, and Dresden; in the autumn he accepted a call from the Jewish community in Mannheim.

In July, 1864, Jastrow accepted a call to Worms as district rabbi, and while there he produced Vier Jahrhunderte aus der Gesch.

In the autumn of 1866 he went to Philadelphia as rabbi of the Ashkenazi congregation Rodeph Shalom, with which he was connected until his death, remaining in active service until 1892 and identifying himself with the interests of the Jewish community.

He supported the plan of organizing the Board of Delegates of Civil and Religious Rights and, under its auspices, the Jewish Publication Society (1873).

In 1876 Jastrow fell severely ill, and for some years his public activities were limited by his poor health, which necessitated a stay 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 Jastrow was entrusted with the chief editorship.

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.

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.