Why the Reformation failed in Ireland was, until recent years, a matter for little debate. That it failed was beyond question and that its failure was inevitable was a premise seldom challenged. For many Irish historians, the root of its failure lay in the unswerving faith of a gallant people who resisted the attempts of a conquering force to impose upon them a creed at once heretical and foreign. Indeed, it was not until Brendan Bradshaw initiated a whole new approach to the history of the sixteenth century that this kind of view began to be firmly discarded. Others, like Nicholas Canny and, more recently, Steven Ellis and Alan Ford, have joined Bradshaw in questioning some of the old orthodoxies. The result of these endeavours has been, above all, to uncover the fact that the course of the Reformation in Ireland and the reasons for its failure were infinitely more complex than we once believed and, rather unexpectedly, one of the most tantalising issues raised by the debates which Bradshaw’s work has provoked has been the problem of precisely when the Reformation may be said to have failed in Ireland. Bradshaw and Canny have conflicting answers to that question and some of them will be considered here.