The international mobility of highly skilled workers is increasing in scale and complexity as more economies participate in R&D and innovation activity. Mobile talent diffuses knowledge both directly and indirectly across borders. This can boost global innovation performance, with benefits accruing to both sending and receiving countries. It is clear that mobility is leading to an increasing level of labour-market internationalisation and integration, and competition for talent is now influencing innovation policy initiatives across the globe. Most countries offer a range of policies focused on assisting and encouraging mobility, although few have a specific and coherent mobility strategy. Many nations aim to attract the same pool of highly skilled talent; thus, relying on international flows to fill existing or future gaps in supply may entail risks. Addressing shortcomings in national policies that may limit domestic supply of skilled workers, and ensuring that the wider environment for innovation and scientific endeavour is sound, are key policy challenges for countries.