The aim of the thesis is to explain the low rate of self-employment among migrants in the Republic of Ireland and Northern Ireland. Despite efforts at a variety of scales to encourage self-employment and entrepreneurship among migrants, they are less likely to become self-employed in the RoI and NI than non-migrants in these places and migrant populations in other OECD countries. In order to explain the causes of this trend, I gathered data through interviews with 43 migrants in the Republic of Ireland and Northern Ireland, who were either currently, formerly or in the process of becoming self-employed when I interviewed them. The purpose of these interviews was to identify the challenges participants experienced in becoming and staying self-employed. I draw on these interviews to argue that migrants tend to experience the same challenges which characterise the business landscape on the island of Ireland. However, the lack of resources at their disposal tended to compound their experiences of these challenges. To explain this I have adopted a Bourdieuan analytical framework, focusing on the role of the social and economic capitals at the disposal of migrants in generating the above trend. I demonstrated this through an analysis of the two most prominent challenges discussed by participants: weak consumer demand for their goods and services and the struggle to access business finance. Both of these challenges are common in the post-recession RoI and NI, but they were often exacerbated for migrant participants through their lack of social and economic capitals, respectively. A focus on migrant experiences also enabled me to analyse their agency in relation to the constraints which they faced. This involved examining their motivations for becoming self-employed and the practices which they developed through particular spaces in order to develop the capitals which they lacked.