This working paper assesses the ease of immigrants' integration in OECD labour markets by estimating how an immigration background influences the probability of being active or employed and the expected hourly earnings, for given individual characteristics. Applying the same methodology to comparable data across twelve OECD countries, immigrants are shown to significantly lag behind natives in terms of employment and/or wages. The differences narrow as years since settlement elapse, especially as regards wages, reflecting progressive assimilation. Strong differences in immigrant-to-native gaps are also observed across countries, and the paper shows that they may, to a significant extent, be explained by differences in labour market policies, in particular unemployment benefits, the tax wedge and the minimum wage. In addition, immigrants are shown to be overrepresented among outsiders in the labour market and, as such, highly sensitive to the difference in employment protection legislation between temporary and permanent contracts. (Contains 36 footnotes, 1 figure and 10 tables.)