In the pallium the medieval papacy created a mechanism of control over the far-flung bishops of the Latin church, a prerogative by which the popes shared honor and power with local prelates?and simultaneously wielded power over them. Contributing to the sway and oversight of the Roman church, this vestment became part of the machinery of centralization that helped produce the high medieval papal monarchy. The pallium was effective because it was a gift with strings attached. This band of white wool encircling the shoulders had been a papal insigne and liturgical vestment since late antiquity. It grew in prominence when the popes began to bestow it regularly on other bishops as a mark of distinction and a sign of their bond to the Roman church. Bonds of Wool analyzes how, through adroit manipulation, this gift came to function as an instrument of papal influence. It explores an abundant array of evidence from diverse genres?including chronicles and letters, saints' lives and canonical collections, polemical treatises and liturgical commentaries, and hundreds of papal privileges?stretching from the eighth century to the thirteenth and representing nearly every region of Western Europe. These sources reveal that the papal conferral of the pallium was an occasion for intervening in local churches throughout the West and a means of examining, approving, and even disciplining key bishops, who were eventually required to request the pallium from Rome. The history of the pallium provides an enlightening window on medieval culture. Through it one can perceive how medieval society expressed beliefs and relationships through artifacts and customs, and one can retrieve the aims and attitudes underlying medieval rituals and symbols. Following the story of this simple material object sheds light on some of the ways medieval people structured their society, exercised authority, and communicated ideas and values.