This book offers a balanced and pragmatic view of the problems associated with international migration. It assembles contributions from two teams of leading scholars in the field. Part One presents the contribution of the first team which is focused on Europe. Part Two is devoted to the contribution of the second team which draws entirely on the US experience. The two parts of the volume are self-contained and complementary in that they take a different theoretical and empirical perspective. For instance, Part One delves more deeply into the consequences of allowing migrants to have free access to the generous welfare state of European countries, whilst Part Two has more to say on policies repressing illegal migration as there is much more evidence of this in the US than in Europe. Much can be learned by comparing the findings of the two parts and in trying to interpret the asymmetries between Europe and the US in migration policies and perceptions of public opinion on this phenomenon. The comments on the two parts by Giuseppe Bertola, George Borjas, Michael Burda, and Riccardo Faini, as well as the final remarks by Olivier Blanchard, Dani Rodrik and Giovanni Sartori, offer additional insights in this respect.