This theoretical paper adopts the viewpoint of the audience of subtitled films and outlines a theory of subtitles as communicative agents within the participation structures of film reception. Based on examples from three Swiss fiction films, the following communicative effects are found and illustrated: uniformity, authorisation, foregrounding, aestheticisation, foreignisation. These effects are conceptualised in terms of Constitutive Communication theory and textual agency (cfr. Cooren, 2004).