The Catholic Church has been a very important presence in the history of modern Ireland. The seventeenth and eighteenth centuries are in a very real sense the time when it took on the form that made it such a weighty social force in the life of the nation. This publication studies a community moulded by several forces. The two most important were the penal legislation and the mission of tridentine Catholicism. Within it, there were wide diversities of experience, diversities between one region and another, and diversities between the different social classes. The ‘Penal Days’ were indeed penal, but they were not quite the simple story of uniform deprivation that our legend would like to make them. This edition includes an introduction by Prof. Thomas O’Connor which considers the career developments of Patrick Corish as historian, university teacher and writer; his major achievement in revolutionising how church history was taught in his role as professor of modern history at Maynooth (building on the work of his predecessor, Cardinal Tomás Ó Fiaich); his legendary ability as a lecturer; and one of the best known and most respected scholars on the island of Ireland.