This volume consists of a collection of twenty-one papers read at an international conference held in Clairvaux in 2009. As the setting for a conference on the subject of enclosure or enfermement, Clairvaux was uniquely apt since its Cistercian abbey was, for seven centuries, the home of a community of monks who had chosen to live there in claustral seclusion, but in 1808 it was transformed for use as a prison. The theme of enclosure which, for these papers, extends in time from the sixth to the eighteenth century, provides scope for a broad range of approaches and interpretations. Various aspects of enclosure are discussed within the framework of three divergent but complementary viewpoints beginning with the basic concept of confinement and the values attached to it. Secondly, attention is drawn to the practical details of communal living in an enclosed environment and, thirdly, the underlying aims and consequent implementation of enclosure and the effect on those who experienced it in its several forms. An introductory essay written by three of the contributors offers a preliminary clarification necessitated by the recurring use of the terms cloister (‘claustrum’) and prison (‘carcer’) interpreted in different senses, some of them contradictory: as the papers demonstrate, for some individuals the cloister was seen as a prison while for others the reverse was true. The fundamental difference, however, is that the monk has chosen his way of life, but the prisoner has had his forced upon him.