This course explores different ways in which groups of people lived as Christians, but not fully as part of the official “approved” church, between c. 1000 and c. 1500 in Western Europe. In theory, every Christian baptized at this period entered a lifelong binding obligation of loyalty to the Church led by the Roman Papacy. Yet many were also born into dissenting traditions of various kinds, who supported each other through semi-secret bonds of community. Such people – men, women and children, often of modest means and education – were criminals in the eyes of the institutional church. They left traces of their lives and beliefs because they were, from time to time, brought to trial, interrogated, and for the most part obliged to retract their beliefs, and sentenced to penances. Studying these marginalized, intermittently persecuted people entails interesting challenges of historical method; it also presents a fascinating case-study in the nuances of belief, before belief became a voluntary decision.