Since the discovery in the 1950's of the Barcelona Papyrus, the anaphora contained within it has remained the most understudied classical anaphora. However, a close analysis of this anaphora can reshape liturgical historians' understanding of a number of classical anaphoras, and thus their approach to anaphoral development more broadly. This anaphora requires scholars to rethink questions concerning the construction, geographical provenance, and structural patterns of early anaphoras and their units. It is a witness to a very early form of Eucharistic praying, and points to various ways in which older less developed Eucharistic prayers may have developed into the anaphoral patterns common in the fourth century. As such, an analysis of this anaphora is of historical and methodological interest. This anaphora is also an early witness to Egyptian eucharistic praying. It stems from the same anaphoral tradition as the Anaphora of St. Mark, but on the whole it is a better witness to the earlier form of that tradition. The anaphora in the Barcelona Papyrus also bears a number of structural and textual similarities to the anaphora described in the Mystagogical Catecheses, which is often attributed to Cyril of Jerusalem. As such, it sheds further light on the relationship between Egypt and Jerusalem and provides further evidence in support of Geoffrey Cuming's theory that a "common ancestor" lies behind the anaphoras from Egypt and Jerusalem. Finally, the anaphora in the Barcelona Papyrus, as one of our earliest extant Eucharistic prayers, provides us with evidence for how the earliest anaphoras were structured. In the earliest layers of the anaphora, a structure of Thanksgiving-Supplication can be clearly discerned. Most of the classical anaphoras appear to have been constructed around these two modes of prayer. As Eucharistic prayers came to be written down, this Thanksgiving-Supplication pattern would be expanded and embellished. Over time, this pattern would become disguised in many of the classical anaphoras. This structure can, however, still be clearly seen in the anaphora in the Barcelona Papyrus.