The article traces the constitution, diversification and normalization of the AIDS cause in Switzerland. Particular emphasis is placed on the interactions between the medical field, public authorities and associative space in the fight against AIDS, the latter being understood as the place where individual and collective actors compete to define the cause. We argue that the major phases in the structuring of the struggle, the pace of state intervention and the creation of a multi-organizational field, can only be understood if one adopts a "configurational perspective" (Elias 1939), attentive at each step to the manner in which, in a given context and under the effect of particular constraints, the actors present strategically interact and contribute to transforming their environment and their objective chances of reaching their goals. Such an approach, implies that we take into account the changing socio-biological characteristics of those (volunteers and professionals) who have committed themselves to the cause. It is these successive waves of activists which have helped shape the cause. In turn, internal movement divisions about how to respond to the epidemic as well as the changing perceptions of the disease have contributed to modify the opportunities for commitment, encouraging certain individual kinds of people and excluding others.