The number of immigrants across the world has doubled since 1980. The estimates of the impact of immigration on wages and employment in host countries are quantitatively small but vary widely. We summarize previous meta-analyses of the empirical literature and consider the implications for policy. We conclude that, on average, the impact on employment of the native born is smaller than on wages, while impacts are generally smaller in the US than in other countries studied to date. The variation in the estimates is related to the definition of the labour market, the extent of substitutability of foreign and native workers, and controls for endogeneity of immigrant settlement in statistical modelling. Policies enhancing labour-market flexibility, while at the same time improving immigrant economic integration, are likely to be effective in reducing transitory negative impacts.