In light of evidence that the Internet, participatory media, and online communities are increasingly central to civic and political life, this article investigates online political discourse as a context of youth civic development. Drawing on a national survey of 2,519 youth, ages 15 to 24, we find that exposure to conflict in online discourse is common. Nearly half of youth report witnessing conflict online, although fewer participate directly in these exchanges. We find that youth who are most involved in online political discussions or who get news through online participatory media are more likely to encounter such conflict. In addition, experiences with conflict vary by type of online community: Greater involvement in interest-driven online communities is associated with greater involvement in online conflict, while involvement in friendship-driven communities is not. Finally, we examine youths’ normative reactions to online conflict and discuss implications for youth civic engagement and development.