This study examines a particular modality of audience participation in Japanese municipal council sessions. As with parliamentary debates elsewhere (Carbó 1992, Antaki & Leudar, 2001), the prescribed participation framework in a Japanese council session is highly structured so as to facilitate deliberation for the public good. Accordingly, the formal institutional rules do not assign the audience ratified speaking rights during question-answer periods. Nevertheless, audience members do insert interjectory remarks with precise timings to accomplish specific social consequences. While official records typically exclude audience voices and therefore fail to capture the relevant social consquences, the analysis of raw data brings them to light. This study investigates audience interjections in terms of their sociolinguistic characteristics, their placement in the on-going discussions, and their “covert” social consequences. The analysis shows that interjections in Japanese council sessions are tools for spontaneous politicking whereas the ostensibly deliberative proceedings are largely scripted performance.