This article extends the Uppsala Conflict Data Program (UCDP) by presenting new global data on non-state conflict, or armed conflict between two groups, neither of which is the state. The dataset includes conflicts between rebel groups and other organized militias, and thus serves as a complement to existing datasets on armed conflict which have either ignored this kind of violence or aggregated it into civil war. The dataset also includes cases of fighting between supporters of different political parties as well as cases of communal conflict, that is, conflict between two social groups, usually identified along ethnic or religious lines. This thus extends UCDP’s conflict data collection to facilitate the study of topics like rebel fractionalization, paramilitary involvement in conflict violence, and communal or ethnic conflict. In the article, we present a background to the data collection and provide descriptive statistics for the period 1989–2008 and then illustrate how the data can be used with the case of Somalia. These data move beyond state-centric conceptions of collective violence to facilitate research into the causes and consequences of group violence which occurs without state participation.