In this paper, I account for inhabitants’ involvement in a participatory gathering taking place in Belgium, in the context of a municipal mobility plan. Attention is paid to normative expectations that heavily influence the meetings’ organization, to their possible evolution in the course of events, and to the facilities supporting participants’ memory. In this respect, I point out the requirements of cartography, a central tool in this case, and the resulting formatting process. In this framework, I look at a regularly observed phenomenon in this kind of meeting: the gradual defection of participants.