This module aims to introduce students to the concept of heresy, and to its development during the High Middle Ages into different forms of dissent, ranging from behavioural to doctrinal and political non-conformity. During Semester 1, the students will become familiar with the main historical context, problems of historiography, and theoretical issues. The complex nature of historical analysis, which has been driven by on the one hand Protestant concern to use Medieval heretics as a continuous line of witnesses to truth between the Apostolic Church and the Reformation, and on the other hand Catholic concern to demonstrate the antiquity of condemnation of heretical error, will be analysed. At the same time, it will be necessary to gain awareness of the appropriate theoretical instruments such as canon law and Medieval theological thought, in order to understand the gradual transformation of what constituted heresy for the Medieval Church. In Semester 2, the focus will shift from heresy to the heretics; here students will investigate the impact of dissent on the life of thirteenth- and fourteenth-century people and institutions. Topics examined will include heresy and family life, heresy and women, the 'lived religion'. For reasons of availability of sources in translation, this second part will necessarily focus on France and Italy in the thirteenth and fourteenth centuries.