This paper explores the importance of occupational downgrading in explaining the pay gap of New Member States ( NMS) immigrants to Ireland by taking advantage of two data sources, the Census and the Survey on Income and Living Conditions ( SILC). The study identifies biases in the coverage of NMS immigrants in SILC that dampen their estimated earnings disadvantage. Corrections to population weights are suggested. These adjustments have a significant impact on results, increasing both the size of the wage penalty of NMS immigrants and the extent to which the pay gap can be explained by occupational downgrading. A replication of published results for the UK reveals similar patterns of penalties for NMS workers in both countries. Factors that may explain the concentration of NMS workers in low-skill/low-wage occupations are discussed. [ABSTRACT FROM AUTHOR]