Through a careful study of P-Isaiah, specifically focusing on several important aspects of the translational text: the status of its Vorlage, its dependence on other ancient versions and books, notably the LXX and the NT Peshitta, and other descriptive questions, such as how the translators dealt with difficult roots encountered in the Hebrew text, this dissertation argues that the translation of the Peshitta of Isaiah is most probably the product of at least two different Jewish-Christian translators, each of whom has their own distinctive style and techniques of translation. The results of this study into the P-Isaiah can bring to light the history of the translation of one of the most important books in the Nevi'im. Through this understanding, the importance of the Peshitta for textual criticism of the Hebrew Bible can also be re-evaluated. Meanwhile, this study will provide us with a new perspective not only on the Christian-Jewish polemic behind the text but also on the positive Christian-Jewish relationship in the eastern Syriac world.