It is widely recognised that knowledge and highly-skilled individuals as “carriers” of knowledge (i.e. knowledge spillover agents) play a key role in impelling the development and growth of cities and regions. In this chapter we discuss the relation between the mobility of talent and knowledge flows. In this context, several issues are examined, including the role of highly-skilled labour for regional development and innovation, the essential features that characterise knowledge spillovers through labour mobility, the key factors for attracting and retaining talent as well as the rise of “brain gain” policies. Although this chapter deals with highly-skilled mobility and migration in general, particular attention will be paid to flows of (star) scientists.