The act of 1704 ‘to prevent the further gronth of popery’ was, in Lecky's words, the most notorious of the penal laws. It was also the most comprehensive. It covered changes of religion, the purchase and inheritance of land, education, guardianship, employment, voting and pilgrimages. It was from the first regarded as an important and highly controversial measure. There was a great deal of argument about it, and its form changed remarkably during the protracted proceedings that took place before it passed into law. Catholics opposed it strenuously at various points in the legislative process. The introduction, at a late stage, of the sacramental test hit dissenters and produced further controversv. There were a number of unusual features in the treatment of the bill which repay investigation of the considerable volume of material relating to it. There are also gaps in the evidence which make it difficult to be certain about such questions as the attitude of the English government of the day to penal legislation in Ireland. It is particularly hard to determine why, and by whom, the sacramental test was introduced into the bill.