Sociological or historical surveys on French elites highlighted at many occasions that “grandes écoles” graduated are overrepresented at the top of the socio-professional hierarchy. These surveys showed that social capital constituted by passing through an elite higher educational institution and the co-optation networks among graduates from the same institution is a key asset to reach these prestigious social positions. But little is know on the concrete activation conditions of such relational resources. Focusing on one “grandes écoles” graduates subgroup (the graduates from one of the Ecole Normale Supérieure), this article aims to better understand how social capital is activated. On the one hand, we show that the legitimate definition of the social link among this graduates subgroup and the dominant norms and representations among the professional groups reached by graduates informs the relational resources activation possibilities.