It has long been known that sheets printed with staves for musicians’ use were widely manufactured and sold across sixteenth-century Europe, but the subject has evaded systematic study, partly because most printed music papers do not bear their printers’ names or marks, partly because no comprehensive census of sixteenth-century music manuscripts exists, and partly because the presence of printed staves can be hard to detect, especially from an inexact surrogate such as a microfilm or monochrome photograph. As colour digital images of library holdings become increasingly accessible online, so research into this subject itself becomes increasingly viable. However, the opportunities are balanced by some significant challenges. For instance, how should the papers be described, categorised and differentiated from one another? How can their printers be identified? How do we proceed if a printer issued more than one ‘edition’ of what was essentially a stable design, perhaps over the span of a decade or more? These and other broad questions are addressed in this chapter, which draws its examples and data largely from two local repertories, both now viewable online. The first is English manuscripts of the period 1575–1596, the twenty-one-year span during which the supply of printed music papers in England was controlled by a royal monopoly granted to the musicians Thomas Tallis and William Byrd. The second is the various partbooks and partleaves formerly owned by Johann Heinrich Herwart (1520–1583) of Augsburg, now variously in the Bayerische Staatsbibliothek and the Bibliothèque nationale de France; these supply a useful sample of printed music papers available in northern continental Europe.