The thesis assesses the development of the Catholic community in the Western ecclesiastical province of the Catholic Church in Scotland. It examines ecclesiastical developments, and also the specific impact of the Irish Catholic migrant: why, and when they came, in what numbers, and what reaction they received from native Scots Catholics and society at large. The response of the church in providing places of worship and clergy is discussed; as are the provision and impact of education and social welfare, and the consequent financial burden. The ability of the church to confirm and retain the religious commitment of its community is also examined, in the context of such problems as leakage and nonpractice, and in the face of the perceived threat represented by socialist, communist and secular ideologies. Through societies like the League of the Cross, the St. Vincent de Paul Society, and the Catholic Truth Society, the Catholic community sought to provide an all-embracing community life and ethos. And yet the thesis questions how effective such a policy could be in practice. Given the existence of issues like Irish Home Rule presenting an alternative focus of political loyalty, and the impact of gradual social and occupational change upon its adherents, a policy of exclusiveness could not prevent the permeation among the Catholic community, and its leaders, of the ideals and expectations of the civil society in which that community was placed. As in other cultures, the Catholic community in West Central Scotland had to resolve its own internal dissensions and difficulties, and to define its relationship with society at large.