In the sixth century, emperors, kings, and bishops discovered the monastery as a tool of government. In particular, this century saw the transition of confinement in a monastery from a voluntary form of penance to a legal penalty. Recent scholarship has very much concentrated on the role of civic rulers in this development. This article investigates a bishop's view on and practice of monastic confinement. Some of the most detailed evidence for the employment of both clerical and lay monastic confinement in the sixth century comes from the letters of Gregory the Great (590-604). They provide a unique case study of episcopal engagement with Roman criminal law at a time when bishops in general, and the Roman bishop in particular, increasingly assumed a role in civil judicial administration. They also show that Gregory's interest in the monastery lay mostly in its ability to provide a (sometimes temporary) space for the correction of everyone—clergy, ascetics, and lay people alike. The article demonstrates that Gregory employed the sentence of monastic confinement as an extraordinary form of structured penitential routine for stubborn offenders within his larger program of pastoral flexibility.