In social dilemmas, leading a team by making heroic efforts may prove costly, especially when the followers are not adequately motivated to make similar sacrifices. Attempting to shed light on what drives people to lead, we devise a two-stage public good experiment with endogenous timing. We show that leading by making generous contributions is widespread and relatively persistent. At least three motives explain this behavior. Some use leadership strategically to distill personal gains, with the expectation that others will respond by being at least as generous. Others are more altruistic, volunteering to lead even though this may come at a personal cost. Yet for another fraction of volunteers, a concern for maintaining a positive social image appears to be responsible. We also find that voluntary leaders are not necessarily more influential than randomly-chosen leaders.