In this work, Paul O'Leary examines the causes of emigration and seeks to understand the experience of Irish immigrants in Wales. Initially, there was little evidence of Celtic solidarity and the Irish often met with violent hostility from the Welsh. Nevertheless, by the late 19th century the tortuous process of integration was well under way and appeared to be relatively trouble free in comparison with the Irish experience in many other parts of Britain. The author considers key aspects of immigrant life in depth: pre-famine immigration; the role of the Irish in the labour force; criminality and drink; the establishment of community institutions ranging from Catholic churches and schools to pubs and bookshops, from friendly societies to political organizations; the mobilization of support for Irish nationalist organizations; and Irish participation in the labour movement. In each case the author links the distinctive experiences of the Irish to developments in Welsh society.