This study analyzes the ways in which the pallium, a liturgical vestment and papal insigne, functioned as an instrument of power when shared by the popes with other bishops. Drawing on precedents from late antiquity, especially those of Gregory the Great, the medieval papacy defined the role of this woolen band during the Carolingian age (741–882). Its conferral became an occasion for intervening in local churches throughout the Latin West and a means of examining and approving key hierarchs, who were eventually required to request it. This gift created relationships of familiarity and subordination with its recipients, altered their standing among their fellow prelates, and affected the interests of secular rulers. Its usual (but not exclusive) association with metropolitans made it a badge of their office, needed for exercising their authority, and the popes restricted the pallium as a personal privilege and regulated its proper use in order to cultivate dependence. As a contact relic from St. Peter's tomb and the subject of creative interpretations, the vestment was invested with value and meaning that supported its role and implied an ideal of pastoral behavior.

This pattern continued in the following years (882–1046), as enshrined in canon law and the liturgy and negotiated in various political circumstances. Now a routine part of the ecclesiastical system, some customs surrounding the pallium suffered mismanagement by negligent popes, and at times it threatened to escape their control. Other popes, however, introduced innovations that enhanced and adapted previous practices. The use of the pallium reached its climax in the reform era (1046–1119), when the papacy's new energy and focus employed it as a tool for Church-wide change. In an effort to combat contemporary abuses, the popes harnessed the vestment in new ways to extend their influence, control the episcopate, and establish bonds of loyalty. They encouraged new thinking that deepened its traditional significance and cast it as “the fullness of the pontifical office,” freely bestowed by the apostolic see. Contributing to the sway and oversight of the Roman church, the pallium was part of the machinery of centralization that helped to produce the papal monarchy.