The evidence for clerical behaviour at the end of the Middle Ages has a Delphic ambiguity about it: the detecta and comperta of visitation records speak only of shortcomings; depositions in court are testimony and, for the historian, not proof; verdicts and penalties are often unrecorded; most ambiguous of all is the significance of purgation. It is hardly possible, therefore, to say whether crimes and misdemeanours among the clergy were increasing, not only because the sources are equivocal, but also because they are fortuitous, and before 1400 much less abundant. It is impossible to speak in modern parlance of a crime wave: conditions in the fifteenth century may or may not have been normal; what is certain is that they were not ideal. The aim of this chapter, therefore, is to see how far the Church tried to improve discipline and if and why these attempts failed: whether the bishops or their deputies were aware of a new situation, or whether they failed to perceive the critical nature of a familiar condition, whether they yielded to panic or complacency, whether they misjudged the relative gravity of different abuses, and whether their weapons were inadequate for the task of correction.