This monograph explores the history of the Coptic tradition of John's gospel, considering when these ancient Egyptian witnesses are profitable for determining the earliest readings of their Greek source text. The standard critical edition of the Greek New Testament cites the Coptic versions no fewer than 1,000 times in John's gospel. For these citations, that edition references six dialectally distinct Coptic translations: the Achmimic, Bohairic, Lycopolitan (Subachmimic), Middle Egyptian Fayumic, Proto-Bohairic, and Sahidic versions. In addition to examining these, this project considers newly published texts from the Fayumic and Middle Egyptian traditions. Apart from a pivotal article on Coptic and New Testament textual criticism by Gerd Mink in 1972, Coptological research has progressed with only limited contact with Greek textual criticism. The discovery of various apocryphal Christian texts in Coptic translations has further diverted attention from Greek textual criticism. This project contributes to this subject area by applying recent advances in Coptology, and exploring the various facets of the Coptic translations. In particular, the monograph investigates (1) translation technique, (2) Greek-Coptic linguistic differences, (3) the reliability of the Coptic manuscript tradition, (4) the relationships between the Coptic versions, and (5) relevant contributions from the scholarly community. John's gospel is extant in more Coptic dialectal versions than any other biblical text. As a result, the gospel offers unique insight into the nature of the ancient Egyptian Christian communities.