In response to their critics, deliberative theorists have increasingly paid attention to the conditions that make democratic deliberation possible. In so doing, however, they have largely neglected what it is that deliberation actually does. This paper is an attempt to bring reflection on deliberation back into the theory of deliberative democracy through the work of Hans-Georg Gadamer. Building on the recent accomplishments of deliberative theorists, I use Gadamer's phenomenology of conversation to highlight what deliberation does — that is, what takes place when dialogue leads to understanding in politics. The novelty of this approach lies in its shift in focus away from the conditions for deliberation and to the dialogue itself. This shift reveals that theorists of deliberative democracy simultaneously demand too much and expect too little: they demand too much from citizens in terms of the attitudes and dispositions required for deliberation, but they expect too little in terms of its results, content with accommodation or mutual respect rather than seeking understanding or transformation. I argue that Gadamer's approach deepens and extends the insights of the deliberative theorists by showing us how dialogue discloses a common subject, creates a common language, and puts our prejudices at risk.