The following article explores some of the ways in which the leaders of a medieval ecclesiastical institution, in this case Bury St Edmund, could construct that institution’s own identity by textual production that was centred on the figure of their patron saint, Edmund Martyr. This textual production, and the formulation of Saint Edmund, underwent a continuous development from 1065 onwards, which can be most clearly seen in the composition of the liturgical office for Edmund’s feast day. By an examination of three examples taken from this office, I aim to demonstrate some of the ways in which the figure of Edmund was altered, how the narrative of his passion story was developed and what audiences these changes were aimed at. The purpose of the article is to emphasise the function of the office as a vehicle for the construction of institutional identity in the Middle Ages.