Ireland and Italy saw significant proportions of their populations emigrate after 1945 before becoming host to substantial immigrant populations in more recent times. Despite the post-war exodus of millions of Irish and Italians, the literature has consistently failed to quantify the effect this had on Irish and Italian society and on the people who left. Not enough attention has been devoted to examining how Ireland and Italy have adapted to their transitions from near homogenous to heterogeneous societies in such a short period either. Immigrants today amount to over half a million in Ireland (12% of the Irish population) and 4.6 million in Italy (8% of the Italian population). These countries’ transitions from near monocultural to multicultural societies in such a short period demands scholarly attention. With the departure of young people from Ireland and Italy once again because of reduced opportunities at home, and with newcomers still arriving in search of a better life, this comparative project will provide a timely indicator of how emigration and immigration have shaped the two societies since 1945.The main objective of this project is to demonstrate how emigration and immigration have shaped Ireland and Italy since 1945. To fulfil this aim, the study will consider, in detail, (1) why so many people left Ireland and Italy after 1945. It will assess (2) the ramifications of the exodus of millions of Irish and Italians for the societies they left behind. It will explore (3) the effects that migration had on those departing their homes. In an attempt to fill a notable gap in the literature, this project will examine (4) how return migration and internal migration effected Irish and Italian society in the 1960s and 1970s. Relating to more contemporaneous developments, this study will endeavour to investigate (5) how Ireland and Italy have adapted to recently becoming hosts to sizeable numbers of immigrants.