This case study was conducted as part of the documentation of a research partnership. It aims to understand the development of the investigated team using the concept of interdependence, defined as the mutual valorization of each partner’s resources. The results highlight the nature of the resources valued by partners, and the importance of negotiation in the construction of this valorization. Following this analysis, we propose to apprehend the notion of expertise not as an individual characteristic, but as a social construct made possible by the meeting of mutually interested parties.