This article presents the collation map, a new diagrammatic method for visually mapping the texts of complex medieval Western manuscripts against their material structures. It argues that the collation map is a more useful tool for understanding the collation of codicologically and textually complex manuscripts than collation formulae – currently the most frequently used method of representing collation. Four reasons for this are explored: one, the map provides a visual representation of the manuscript’s overall structure at a glance by showing the whole manuscript on a single page; two, it provides an instant overview of the size and spread of texts between quires, recognizing the importance of manuscript contents both for collation and for the growing movement to view manuscript books as whole objects; three, it is a useful working aid when examining digital manuscripts, and an essential aid to scholarship in an increasingly digital and international environment; and four, unlike formulae, the collation map avoids prescribing a set of theoretical standards or a national system. The article couches these discussions within the context of the full range of published work in theoretical codicology.