Negative campaigning is a worldwide phenomenon. As a strategy for mobilizing support, it affects the electorate and democracy. However, its effectiveness varies across space and time. While some studies assert that negativity depresses voter turnout, thereby delegitimizing the electoral process, others provide conflicting results that such campaigns mobilize voters since they supply information critical for their participation. There are three nuanced outcomes resulting from negative campaigning: the target electoral support diminishes; the attacker in a negative campaign experiences a backlash; or, when multiple candidates or parties compete, a negative effect on the target of the attack, coupled with a backlash effect on the attacker, may benefit the other candidates, who refrained from going negative. This article reviews the state of the scholarship on negative campaigning and its impact on democracy. It sheds light on a rapidly evolving field of political science and communication research.