For a decade now, technical changes in management and economy have driven people in charge of projects and companies to gradually substitute the word "competences" for the word "qualification" to cope with the task of adapting people to jobs and objectives, and to seek procedures or formats to assess such competences. But, right though we may be in putting forward the issue - even beyond the current economic situation - such a quest for out-of-context, homogeneous and easy-to-codify procedures or diagrams is inconsistent with the numerous levels or elements to be put together in any working activity. There are at least three quite different sides to a working activity: the extent to which conceptualizable knowledge can be reached, the extent to which the very historical aspects of a situation can be understood, and the clash of values with which any individual is confronted in a given working environment. Hence the basic heterogeneity of the components of competency, of the dynamic relationship between these components - which can never be actually foreseen - and thus of the research to be done on the various formats of assessment suited to the variety of those components.