This paper aims at examining the construction and utilisation of the knowledge and know-how embodied in their professional competence by a particular category of agents, namely engineers. In their capacity as the principal creators of new knowledge, members of this category are regarded as strategic players in technological innovation. This population is generally regarded as a standard category endowed with both generic human capital based on the acquisition in the higher education system of high-level abstract knowledge and with a set of highly standardised professional skills. They are assumed to behave as ‘professionals' in occupational labour market (OLM) and, implicitly, as archetypal ‘rational agents' in the wage competitive model. Based on canonic Mincer's model, we seek to measure the return to job tenure, which approximates more or less to the employer policy of building loyalty within a firm's engineering population, and the return to professional experience in the external labour market. Comparison of these two indicators and the addition of mobility as a third indicator will permit us to assess the extent to which the notion of OLM and/or the professionalism model can be applied to the five European countries (France, UK, Denmark, Belgium and Spain) in our sample and to Japan.