The implementation of religious Reformation in the new Kingdom of Sweden required the local clergy to reinvent their working library, and many of the medieval parchment manuscripts of liturgical music ended up recycled as covers for bailiff’s books during the sixteenth and seventeenth centuries. This change was not immediate, however, as some of the surviving fragments bear signs of their content being refashioned to fit the new aspects of Reformation liturgy. Furthermore, parchment fragments from sources made after the Refor-mation survive, containing liturgy for the Mass in Swedish, and attesting to the continued appeal of the material format. My chapter examines techniques of reworking parchment fragments and their musical repertory for the purposes of the Reformation worship.