Divided societies emerging from conflict are found around the globe, and these divisions can cause, and may be perpetuated by, disunity in educational provision. Establishing sound and equitable education is considered vital in promoting reconciliation in places with apparently intractable conflict. Northern Ireland was involved in ethno-sectarian violence for 30 years. Society there is still fundamentally divided and there is considerable duplication of services supplying the needs of each community. This is true also of education with multiple schools each catering for 'their own' population. Sometimes these can be too small to be sustainable and/or may be inefficient. In this research GIS analysis is used to identify 32 pairs of primary schools and their levels of sustainability are estimated, alongside some additional cost of the duplication, although this can be difficult to quantify. Bringing schools together in a society emerging from conflict will not be easy for communities. However, economic costs may drive difficult structural change. Perhaps an even more important driver, in addition to financial costs, is the less tangible but even more important costs to future social cohesion should separation continue.