The present work traces the history of the ante-penultimate blessing of the Amidah, “Birkat ha-Avodah”, from Second Temple times through the Middle Ages. The first chapter deals with the rabbinic sources that describe its recitation in the Temple and compares versions of the blessing found in siddurim with prayers found in literature from the period of the Second Temple. The second chapter is devoted to the early evidence of the blessing’s formulation located in the 4th century church order, The Apostolic Constitutions. In the third chapter, all of the various versions of the blessing located in siddurim and in medieval halakhic literature are analyzed.  In the fourth chapter, he utilizes a variety of sources, including a large corpus of classical Piyyut, to reconstruct a lost version of the blessing’s doxology. The fifth chapter unpacks the language of cultic worship utilized in the various versions of the blessing and compares it with the understandings of the blessing’s meaning found in classical Piyyut and in medieval sources. In the summary, he provides a new model for understanding the development of the version of the blessing that was eventually adopted and address the ramifications of this study for our understandings of the development of Jewish liturgy and of the substitution of sacrifice in Jewish thought.