This study significantly broadens our understanding of the migration process by placing a form of associational behavior in the wider historical context of leaving one country and settling in one of two destinations, in the decade and a half after World War II. Taking the Irish as a case-study, the aim is to explore the impact that choosing New York over London had, in how migrants made the transition from the homeland and adapted to migrant life. The focus on county associations, common to both cities, facilitates a comparative level of analysis. These associations allow us to excavate experiences in a way that sheds light on migrant responses on the individual level and in a collective sense, and in this way it is an innovative way of presenting the history of ethnic communities. A combination of written material and oral sources allows for the presentation of specific characteristics which impacted on experiences. It shows how the different histories of Irish migration to New York and London, the geopolitical influences and the roles of socio-political dynamics all shaped how the Irish responded to the environments in which they found themselves. Through these associations, we see an ethnic community adapting a structure to recreate a semblance of what life was like in the homeland. The comparative frameworks provided a means of highlighting the similarities and divergences between the locations. The narrative shows that while county associations were broadly similar in terms of their format and membership profiles, the environments in which they operated diverged significantly and this variation reflects the tension that has differentiated Irish London from Irish New York for at least the latter half of the twentieth century. This study makes an important contribution to the Irish diaspora history. More importantly however, this thesis provides a case-study which broadens our understanding of, and approach to, documenting migrant experiences. It does this by presenting factors that shape associational practices in migrant communities and by demonstrating how associational behavior has implications for issues like identity and allegiance.