This introduction to the ‘Spaces of Irish Catholicism’ Roundtable argues that applying the concept of ‘space’ to nineteenth-century Irish Catholicism has the potential to offer significant new insights to our understandings of Irish Catholicism and the lives of ordinary Irish Catholics, but also to Victorian Studies and religious history more generally. In particular, it contends that the nature of Irish Catholicism in the later nineteenth century was such that examining its many different spaces offers a valuable means of enacting Peter Andersson’s plea to uncover the ‘backstage’ of the Victorian period. In describing the eight diverse papers that comprise the Roundtable, the introduction argues that a previously identified dichotomy between the ‘poetics of space’ and the ‘politics of space’ within the religious realm may need to be rethought.