This paper examines the evolution of the state-supported denominational education system in Ireland in the context of increasing social diversity, and considers the capacity for incremental change in a system of institutional pluralism hitherto dominated by a single religion. In particular, we examine challenges to the historical arrangements emerging in two recent contentious issues: cuts in special funding for Protestant secondary schools and proposed diversification of the patronage of primary schools, revealing pressures on the dominant role of the Catholic Church and on the privileged place of religion in education. We identify a shift towards a more varied pluralism, or greater "diversity of schools", in which multi- or non-denominational schools now feature more prominently, rather than towards either a secular system or privileged recognition of religious schools. These developments entail a change in the historical balance of religious equality and freedoms: from leaning more towards collective religious freedom and equality among religions, to tilting more towards individual religious freedom and non-discrimination. Yet the limited possibilities of incremental change are suggested by delays in changes of patronage, and the emerging balance displays continuing tensions between individual and collective freedom, clustered around "diversity in schools": the integration of religion in the curriculum, religious instruction in the school day, and the accommodation of children and teachers of other beliefs in religious schools.