The international mobility of professionals and graduates is one of the most dynamic transnational types of movement and represents an increasingly large component of global migration streams. The global competition for talent, the expansion of the knowledge economy and the increasing globalisation of markets and companies contribute to the increased importance of these mobility flows. Yet academic debates persist around who and what is meant by ‘highly skilled’. This paper highlights the importance of social context and immigrant agency in the assessment of skills and human capital. It draws attention to the substantial difference between ‘highly skilled’ and ‘highly qualified’ immigrants. The analysis presents original empirical data collected in 2005 through an online survey (N=133) and 54 semi-structured interviews with East European professionals and graduates living and working in London. It argues that the social aspects of skills are essential components of skill construction, especially in the changing social contexts of migration. It concludes that being skilled is an outcome of negotiations around the value and the value-attached significance of employable human capital. The negotiators are, on the one hand, the highly qualified migrants themselves and their ways of self-representation of the value of their credentials, knowledge, skills and abilities; on the other hand, they are the employers and their ways of perception, assessment and judgement of employable human capital.