We exploit naturally occurring variation in the existence, closeness, and dissemination of pre-election polls to identify a causal effect of anticipated election closeness on voter turnout in Swiss referenda. Closer elections are associated with greater turnout only when polls exist. Examining within-election variation in newspaper reporting on polls across cantons, we find that close polls increase turnout significantly more where newspapers report on them most. This holds examining only “incidental” exposure to coverage by periodicals whose largest audience is elsewhere. The introduction of polls had larger effects in politically unrepresentative municipalities, where locally available information differs most from national polls.