This article provides a self-analysis of a failed experiment to compare public participation professionals in France and Quebec. The difficulties encountered show us that the circulations of participatory devices and actors across these two spaces do not enable the comparison of their professionals. On the contrary, these circulations give the illusion of a shared universe of meaning and practices. As such, they remind us that the categories of comparative analysis are never given but have to be constructed, through a comprehensive comparison that is sensitive to meanings and national institutions. Such an approach seems to be more important than the researchers being key players in the area of public participation professionals. Also, even though we failed to compare the public participation professionals of France to those of Quebec, our experience has been particularly fruitful in enabling us to better understand the French situation. Looking at Quebec allowed us to see and question elements that we did not, or no longer, perceive.