"Demonstrations" (e.g., direct quotations, conversational facial portrayals, conversational hand gestures, and figurative references) lack conventional meanings, relying instead on a resemblance to their referent. Two experiments tested our theory that demonstrations are a class of communicative acts that speakers are more likely to use in dialogue than in monologue. We compared speakers' rates of demonstrations in face-to-face dialogues, telephone dialogues, and monologues into a handheld microphone or recorder. Experiment 1 confirmed that the proportions of speakers' direct quotations and facial portrayals were (1) significantly higher in the two dialogue conditions than in the monologue condition and (2) not significantly different in the two dialogue conditions. Experiment 2 found the same patterns for the rates of figurative references and hand gestures. In both experiments, regressions confirmed that the increase in demonstrations in dialogues was independent of any effect of visibility.