Our contribution focuses on qualified migrants, or executives on professional mobility in international companies whose employment depends on a solid linguistic capital of skills in several languages. As such, these temporary migrants who are social actors in the community the company represents, are implicitly or explicitly subject to certain rules governing communication within the firm (Thamin, 2007). The issues addressed here concern firstly the mobilising of their plurilingual competence in professional situations, and secondly the functions executives attribute to the languages comprising their linguistic repertoire and the social affiliations they allude to. The results presented here pertain to a collective research project being carried out at present and titled : Biographies langagières et mobilité professionnelle : recomposition des répertoires plurilingues (Language biographies and professional mobility : reconstruction of plurilingual repertoires – our translation), involving 50 questionnaires collected from salaried executives in 15 international firms in the Rhône-Alpes region. We will analyse in particular the composition of their plural repertoires, the competences declared by the subjects themselves in the “official” languages of the firms (French and English) , but also the way employees perceive their plurilingualism in terms of personal identity and social affiliation. The study attributes importance to partial competences and to the way the latter are mobilised and transformed in the workplace.