A new paper in the QJE [the Quarterly Journal of Economics], The Global Race for Talent: Brain Drain, Knowledge Transfer, and Growth, by Marta Prato uses extensive data on inventors and their migration to make the following points. (i) gross migration is asymmetric, with brain drain (net emigration) from the EU to the United States; (ii) migrants increase their patenting by 33% a year after migration; (iii) migrants continue working with inventors at origin after moving, although less frequently; (iv) migrants’ productivity gains spill over to their collaborators at origin, who increase patenting by 16% a year when a co-inventor...