This thesis seeks to establish how welfare payments are provided in Ireland for two categories of migrants: mobile European Union citizens; and third-country national labour migrants; the barriers that restrict their access to the welfare system, and the extent to which the process of ‘Europeanisation’ has affected welfare provision in Ireland for both. In order to achieve this, the thesis utilises a socio-legal method of analysis, which includes theoretical, doctrinal and non-legal strands. What it finds, is that both the relevant Irish and EU welfare rules are quite restrictive and market-based. However, they diverge in terms of their initial starting points. EU law has primarily universalist ambitions in terms of facilitating migrant access to the welfare state, but this is not reflected within the rules themselves. Ireland, by comparison, became more restrictive as an almost direct consequence of its first significant experience of inward migration. It also establishes that, whilst EU law has developed quite significantly within this field, the impact of Union welfare rules on the everyday behaviour of the Irish State in providing welfare payments is limited, in large part due to the Irish State’s lack of technical expertise in EU, and national, welfare law, and the way in which the administration continues to operate. In almost every other respect, Ireland would appear to be a strong example of the impact of Europeanisation. Finally, the thesis argues that this lack of technical expertise, and the opaqueness of the Irish system, create the most significant barriers to accessing welfare payments for both categories of migrants - despite the different legal regimes that govern each of them. Specific barriers do arise for both categories, but these are of lesser significance than the highly opaque and often arbitrary way in which Irish administrative procedures operate at the micro level.