This study on the boy bishop's feast in western Europe deals with a subject that has been hitherto neglected by medievalists. It is situated between different fields of research: the study of rituals and festive culture, the history of pre-modern theatre and liturgy as well as the history of childhood. The book tackles this subject from a geographical and temporal macro-perspective, covering iconographical and textual documents belonging to 150 different institutions (cathedrals, cloisters, schools) from the 11th to the 16th century. In contrast to a rather misleading perspective of scholars who regarded the feast as an element of the culture of laughter and indirectly associating it with carnival, this study shows the boy bishop's feast as a liturgical feast that was closely linked with the cult of the Holy Innocents and Saint Nicholas. Thus the book provides new insights into the late medieval culture of piety as well as religious ritual and concretises the inherent logic of liturgical festivals, which gradually became enhanced and transformed outside the liturgy. The book also contributes to the history of childhood by looking at the role and function of children in medieval clerical communities. There the boy bishop's feast not only was an occasion for joy and play, it also prepared the children for their roles in later life and helped the hole community to rememorize the salvation story as well as universal Christian virtues - like innocence, humility and purity - which the boy bishop impersonated.