© 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group. The `two worlds of morality politics¿ framework suggests that the historical structure of the party system has a major influence on the politics of morality issues. This study uses the case of Ireland to examine that proposition. Ireland is unusual in that it combines the absence of an historical church-state conflict in its party system with an historically strong Roman Catholic Church. It is therefore a `critical case¿ for the `two worlds¿ framework, which brings to the fore the interaction of the Church and the party system. It is also a puzzling case in the timing and sequence of its reforms. Focusing on the politics of contraception, abortion, same-sex marriage, and divorce, we show that the Church had no strong secularising opponents (`enemies¿); however, when public attitudes changed and when liberalising interest groups mobilised, nor did the Church have parties who were close allies (`friends¿). Case studies of abortion and same-sex marriage show in greater depth how, in the presence of changing attitudes and mobilisation, the Church lacked a foothold in the party system that would allow it to obstruct reforms. The study¿s findings open a conversation between the heretofore separate literatures on morality politics and Church influence.