This article focuses on the trouble experienced by researchers who observe participatory practices. It is caused by the nonattendance of some potential participants and by an inability to recognize an important portion of the participants’ contributions. The authors begin by considering the limits of participatory inclusion, providing an overview of the diverse perspectives of the main theorists of public democratic space on the topic. To facilitate comprehension of this issue in forthcoming inquiries, the authors suggest an empirical and conceptual apparatus focused on the idea of threshold. It is both a limit-space and a critical space, and it is particularly relevant to research on participation.