This article describes and analyzes patterns of lethal violence in Darfur, Sudan, during 2008-09, drawing upon a uniquely detailed dataset generated by the United Nations-African Union hybrid operation in Darfur (UNAMID), combined with data generated through aggregation of reports from open-source venues. These data enable detailed analysis of patterns of perpetrator/victim and belligerent groups over time, and show how violence changed over the four years following the height of armed conflict in 2003-05. During the reference period, violent incidents were sporadic and diverse and included: battles between the major combatants; battles among subgroups of combatant coalitions that were ostensibly allied; inter-tribal conflict; incidents of one-sided violence against civilians by different parties; and incidents of banditry. The conflict as a whole defies easy categorization. The exercise illustrates the limits of existing frameworks for categorizing armed violence and underlines the importance of rigorous microlevel data collection and improved models for understanding the dynamics of collective violence. By analogy with the use of the epidemiological data for infectious diseases to help design emergency health interventions, we argue for improved use of data on lethal violence in the design and implementation of peacekeeping, humanitarian and conflict resolution interventions.