This chapter examines papal–imperial relations during the thirteenth century. It focuses on series of oaths sworn by prospective emperors to popes from Innocent III (r. 1198–1216) to Nicholas IV (r. 1288–92), part of broader negotiations over imperial rights on the Italian peninsula and obligations toward the Papal States. Historians often associate this era with the apex and subsequent decline of the so-called medieval “papal monarchy,” as characterized above all by its dramatic conflicts with the rulers of the Holy Roman Empire. The history of those solemn pledges allows us instead to discern a remarkable continuity in papal attitudes toward imperial monarchs, envisioned as partners in the reform of the Church, the defense of the faith, the eradication of heresy, and crusades to recover the Holy Land. By the late thirteenth century, however, for reasons endogenous to their respective spheres of influence, both parties began to lose interest in the realization of those increasingly anachronistic oaths.