Publisher Summary This chapter explores the benefits of international mobility for research and development. Spending a period abroad to pursue training and/or work opportunities can be very beneficial, not only to the scientists themselves but to their employers, their home countries, and society itself. Scientists have globally marketable skills. This can be demonstrated by mapping individual moves. A second way to demonstrate the transferability of scientific research skills across national borders is to identify the countries of origin of the students, postdoctoral fellows, and scientists working in a single institute at a single point of time. Migration patterns between countries or between regions of the world are not necessarily balanced. For example, if one looks at exchanges between candidate countries and the EU that were funded by the European Commission Research Directorate's “Fifth Framework Program” (1998–2000), 18% of EU fellows came from candidate countries to work in EU member states, while only 1.5% of EU fellows from EU member states chose to work in candidate countries. There are several stages in a scientific career when thought can be given to the possibility of studying or doing research abroad. These are at the undergraduate level, the earning of a Ph.D., the postdoctoral phase, the first or subsequent job, and a sabbatical.