International development in the era of globalization needs an effective transfer of knowledge and human capital from the main centres of knowledge creation to developing countries for supporting their growth and development process. Most of the new knowledge is embodied in people (besides goods and capital equipment). Developing countries create or upgrade their qualified human resource base at home through university education and technical training and developed countries ‘import’ technical expertise, professionals and scientists from abroad. This process has raised concern, particularly in developing countries, that have suffered from the flight of educated and talented people (the so-called brain drain). This process, however, needs not be irreversible as people also tend to return to their home country bringing with them knowledge, experience and sometimes financial capital, thereby contributing to national development. In this case, the cycle of emigration-return could be better described as brain circulation. High-skills individuals are often much more internationally mobile, and face fewer restrictions to entry, than unskilled workers. People with skills that are in short supply usually receive favourable visa treatment in rich countries that encourage their international mobility.