Do leaders persuade? Social scientists have long studied the relationship between elite behavior and mass opinion. However, there is surprisingly little evidence regarding direct persuasion by leaders. Here we show that political leaders can persuade their constituents directly on three dimensions: substantive attitudes regarding policy issues, attributions regarding the leaders' qualities, and subsequent voting behavior. We ran two randomized controlled field experiments testing the causal effects of directly interacting with a sitting politician. Our experiments consist of 20 online town hall meetings with members of Congress conducted in 2006 and 2008. Study 1 examined 19 small meetings with members of the House of Representatives (average 20 participants per town hall). Study 2 examined a large (175 participants) town hall with a senator. In both experiments we find that participating has significant and substantively important causal effects on all three dimensions of persuasion but no such effects on issues that were not discussed extensively in the sessions. Further, persuasion was not driven solely by changes in copartisans' attitudes; the effects were consistent across groups.A s thinkers ranging from Aristotle (1) to our own day have argued, persuasion-a change in the attitude or behavior of an individual caused by an appeal from a political elite-is integral to leadership. Although the question of persuasion by leaders is relevant to almost every form of collective human behavior over time and place, there is remarkably little evidence that unmediated, interpersonal appeals from specific leaders affect the attitudes or behavior of individuals. In contrast, the link between indirect, mediated persuasion and mass opinion has been studied intensively (2, 3), with one long-standing literature arguing that elites generally have a minimal impact on mass opinion (4). Others argue that the causal arrow is actually reversed-that political elites are particularly adept at calibrating their statements and political aims in response to their followers' opinions (5, 6).One likely reason for this impasse is that virtually all of the evidence we might use to measure the effects of persuasive appeals by leaders is either indirect and observational, or based on laboratory experiments that only simulate a few features of real elite-mass interactions. Political scientists and psychologists have accumulated aggregate-level evidence of elite persuasion by studying mass media messages and advertising (7, 8), large-N surveys (2, 5, 9-14), and laboratory experiments with hypothetical elite-mass interactions (15, 16). However, there is little publicly available evidence that speaks directly to whether and how individual elites directly persuade their individual constituents. Although the contours of such persuasion may mirror those in the aggregate, and hypothetical scenarios offered in laboratory settings might yield dynamics similar to those in real political interactions, there is reason to think that they do not reliably...