This chapter compares the skill profiles of immigrant and native-born adults for the countries participating in ALL. First, the significance of immigration in OECD countries is considered. Projections forecast declining population growth and for some countries a net decrease by 2050. Second, the knowledge and skills that immigrants contribute to host countries in terms of their educational attainment are examined. Third, the extent to which educational credentials translate into useable skills of the type measured in ALL for the host country is considered. In comparing the education credentials and observed skills of immigrants, it is apparent that there is an education-skills gap among immigrants. In light of this, the potential role of native versus foreign language status in explaining the education-skills gap is considered briefly. Finally, the chapter concludes by studying some of the labour market outcomes of immigrants.