The past two decades have witnessed an unprecedented rise in public policies aimed at hearing children and young people’s voices, which typically entail creating supportive participatory spaces. While this political project is usually presented as a radical move towards a more inclusive society, it raises critical questions about whose voices are being represented, how, why, by whom and for whom. Drawing upon recent ethnographic research on childhood and youth policies in Switzerland, this article explores how children and young people’s voices are produced in concrete situations. It studies how the institutional and material characteristics of participatory spaces and situated interactions shape which voices will actually be heard. The research highlights that, despite their inclusive ambitions, participatory spaces paradoxically exclude young persons who fail to articulate, orally or in written, linguistically, morally or politically legitimate voices.