This thesis explores change in four inner-urban DEIS schools which went from mono-ethnic to multi-ethnic student populations between 2000 and 2010. Lightfoot argues that work in the area of education is 'ahistorical' offering a 'snapshot' of school life. Thus, this research adopts an 'evolutionary view' seeking to unravel changes to key areas of school life over a period of time. In order to explore change, this inquiry employed case studies. Four secondary schools, with 'high' concentrations of minority ethnic students, were selected. Qualitative data from interviews and focus groups was collected. Quantitative data, in the form of enrolment records and Leaving Certificate results were gathered. Official schoolbased documents were also reviewed. The research process unearthed changes to five key areas of school life. It reveals that the classroom became more conducive to teaching and learning, school academic standards improved, and that relations between Irish and minority ethnic students evolved. It further uncovers that staff came to accept a new school identity and that over the ten year period all four schools became inclusive Catholic schools. In general, the changes brought about by the demographic shift in the student populations, were profound and positive.