The definitions used to account for generations within organizations do not generally allow us to understand the intergenerational relationships observed. The notion of exchange that would be the basis of relationships at work does not exhaust the analysis of intergenerational relations either. From a monographic survey in a transport company, this article proposes to use the concept of “professional generation” to account for the temporal construction of social groups. Different professional generations can ignore, influence, or oppose one another. Their cooperation is based on a co-construction of knowledge that enables them to adapt to the evolutions of their professional activity, by articulating the field of experience of the older workers and the horizons of expectation of the younger workers.