Although Ireland has experienced significant inward migration in recent years, the sustained growth of immigration dates from the late 1990s. Schools in this country have played a key role in the integration of immigrant students. Despite an abundance of research internationally in the area of education and integration, how the ethos of a school underpins approaches to the integration of migrant students remains unexplored. This article focuses on how the Catholic ethos of one second level school influences its approach to providing support to young migrants. It emerges from the work of Transnational Collaboration on Bullying, Migration and Integration at School Level (TRIBES), a project focused on migrant experiences of school bullying across the European continent. TRIBES is a European Cooperation in Science and Technology (COST) action, with six working groups across 33 European countries. Ireland is part of a working group focusing on the policies and practices schools adopt to deal with integration of immigrant pupils. While working through the data, researchers noted that two schools in different countries (Malta and Ireland) cited ethos as a significant influence on their approach to integrating migrant students. Moreover, these were the only schools with a denominational (Catholic) ethos. Researchers decided to investigate this further by means of a small-scale case study on the actual influence of ethos on the integration of migrant students. It does not investigate government-led policies around language and academic support, which should be visible in every school with migrant students, regardless of ethos. In Ireland, the case study school self-identified as having a Catholic ethos in the tradition of Nano Nagle and the Presentation Sisters.