Critics, past and present, of state-funded denominational education in Scotland after 1918 have often asserted that the system has promoted social division, separateness and even fostered sectarianism. This lecture – the Cardinal Winning Lecture, 2017, delivered to the St Andrew's Foundation for Catholic Teacher Education, University of Glasgow – disagrees with these views. Instead, the presentation argues that Catholic schooling, in addition to its recognised importance in Christian spiritual formation, has been a crucial influence promoting the integration of a formerly disadvantaged and marginalised community into modern Scotland. ‘Integration’ is defined for this purpose as the process of incorporation into mainstream society as equal citizens. The lecture considers the long and rocky road to this achievement by setting the educational experience within the broader context of Scottish religious, social, political and economic history in the twentieth century.