As people are called to transform data, information and past experiences into effective knowledge, the management of individual competencies will become more and more important in knowledge-based firms. This paper presents both theoretical and practical aspects concerning the management of competencies, based on a seven year field research conducted in a large RD 2) it is impossible to separate the act of competencies' identification from the act of evaluation; 3) relevant competencies emerge from explanation discourses delivered by observers in the attempt to justify their judgement about the performance of an individual within given situations; (4) it is possible, by means of fuzzy logic, to design evaluation support systems (ESS) of competencies by analysing explanation discourses. These assumptions are particularly suitable for organisations operating in a turbulent context, where competencies frequently change.