This thesis consists of three essays in economics of immigration. The first chapter examines the link between the low-skilled immigration and the retirement decision. It shows that the decision to retire dependent on migration via the effect the latter has on the wage and on retirement pension. The crucial element is that the arrival of immigrants brings higher labour income to skilled seniors who may extend their working life and retire later when the pension system is more redistributive. The second chapter presents a reappraisal of the impact of migration on economic growth for 22 OECD countries between 1986 and 2006. It is based on a unique dataset that enables to distinguish net migration of native-born and foreign-born by skill level. In this framework, we identify a positive impact of the human capital brought by migrants on economic growth. The contribution of immigrants to the human capital accumulation tends to dominate the mechanical dilution effect, but the net effect is fairly small, including in countries which have highly selective migration policies. The third chapter empirically examines the link between immigration flow, growth and unemployment in host countries, using a panel VAR approach on data of 22 OECD countries over the period 1990-2006. Such an approach allows us to deal with both data limitation and endogeneity among variables. Our results suggest that immigration flows negatively respond to unemployment in host countries, but do not affect either growth or unemployment in host countries.
