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. 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.