This paper explores some dimensions of the links, or absence thereof, between “official” participatory devices and social and political mobilisations. If filiations can be found, they are often more complex than it seems at first sight, especially since the very notion of “participation” is endowed with very diverse meanings. In contemporary conditions, can these relations be envisioned in terms of complementarity, reciprocal enrichment, or on the contrary, is the development of an “official” participatory democracy somehow a risk for mobilisations? Should not such issues be considered under a different light, including that of a reciprocal autonomy between “institutions” and “social movements”?