Immigrant workers are increasingly essential to the EU economy as Europe's population continues to decline. In Ireland there has been an influx of approximately 250,000 migrants into the country since 1997. Using a recent survey of citizens in the European Union the attitudes of Irish workers towards immigrants regarding their economic, social and cultural impact are assessed. Determinants of attitudinal differences are examined using a number of possible explanatory factors widely recognised in the sociological literature on public opinion formation, such as age, gender and education. The factors with the strongest explanatory effect are education, occupational level, political orientation and political activism. Overall, a sizeable minority of respondents believed that immigrants undermine their country's culture, have a negative impact on wages and the poor and a negative impact on jobs and the economy. Given the consistent upward trend in the number of immigrants into Ireland and the ageing population demographic, such negative attitudes are a major cause for concern for both organisations and for government policy-makers.