The Sadler partbooks – one of only a handful of Elizabethan partbook sets that survives complete, and one of the few Tudor music manuscripts that contain decorative initials, illustrations and Latin inscriptions – are one of the most important English sources for Latin-texted sacred music from the latter half of the sixteenth century. Unfortunately, Sadler’s use of at least one batch of overly-acidic ink has left the partbooks in a fragile state; today they sit closely guarded in the Bodleian Library, notoriously hard of direct access. Consequently, the partbooks have been little studied (until the recent digitisation of the set in conjunction with the AHRC-funded Tudor Partbooks project, the only way of viewing the volumes was via an incomplete set of negative photostats, or a poor quality negative microfilm). This seminar examines how the Sadler partbooks were assembled and copied, probably in rural Northamptonshire between c.1550 and c.1585. It also explores what happened to the partbooks after Sadler’s death, since the volumes today reflect the interventions of perhaps several generations of later possessors, having been re-made (re-decorated; re-coloured; re-ordered; and re-bound) by subsequent owners.