Human resources are to a large extent the key of research efforts, excellence and performances. The number of researchers, as well as their mobility, are two important aspects of this issue. A third one, directly linked, less often addressed, and never at European level, is the question of the researcher profession and researchers careers. This question is crucial, because this aspect of the research system has a deep impact on the way research works. It is especially the case in Europe, because the way, in which research careers are structured and organised in Europe, does not allow Europe to fully exploit its potential in this field