This interdisciplinary study brings together research on audiences’ participation in the media, and an up-close exploration of communicative entitlement of and for such participation. Viewing visitor books as situated, public media, the study asks two related questions: how museums and institutions that employ this medium frame participation of ‘ordinary’ people in the public sphere, and how, in return, visitors variously articulate their participation. The article first examines the context in which visitor books mediate participation, and how museums frame them so (...) as to invite ‘authentic’ expressions by ‘ordinary’ visitors. The analysis depicts a taxonomy of participation, evincing five types of entitlements found in visitor book texts. These entitlements shed light on how participation in the public sphere is both understood and pursued. The article responds to calls for empirically rich studies on mediation practices and processes. It adds to the literature on communicative entitlements by examining an under-researched hitherto public medium and by illuminating a shift from talk-in-interaction to the context of text-in-interaction. (shrink)