Collective vigilantism, group violence to punish perceived offenses to a community, is both global and common in the contemporary world. It is also crucial for understanding state formation, contestation, crime, law and justice, inequality, and racial and ethnic conflicts. We review existing definitions and explanations for collective vigilantism, present a new typology of collective vigilantism that considers both the aims and level of organization of participating agents, and highlight important patterns that emerge from recent research, including the contributions to this special symposium. We present an argument for what a political science treatment of the topic can offer and introduce an ambitious research agenda that builds on cross-cutting themes and puzzles that emerge from the special symposium.