This paper focuses on the presence of the dif-ferent elements of Eusebius’s system of gospel concord-ance in a series of pocket gospel books associated with early medieval Ireland. It provides a brief overview of the pocket gospel book series as a whole and discusses the appearance of parts of the Eusebian system in the Book of Armagh and in the MacDurnan gospels. The addition of the Eusebian apparatus to the Book of Mulling is then examined. The paper demonstrates how the way the apparatus was included in Mulling echoes the close atten-tion to the series that is evident in contemporary Hiberno-Latin texts. It highlights how the marginal references to the Eusebian system included in these gospels provide hitherto neglected evidence for their transmission and for the ways that the gospel may have been read in the Irish medieval context.