This is the first empirical study to explore the ways different types of primary school in the Republic of Ireland integrate children from diverse religious backgrounds. Drawing on semi-structured interviews with principals and teachers, the article focuses on the role of ethos and leadership in the integration processes in one denominational Catholic and two multi-denominational schools. We compare school ethos and enrolment policies, as well as pedagogy and curricular design in religious education across the three types of schools. While the study is carried out in Ireland, it is also of interest to other jurisdictions where schools are faced with increasing religious diversity among their student population.