AbstractAlthough economic inequality has long been viewed as a cause of civil conflict, existing research has not found robust empirical support for this relationship. This study explores the connections between inequality and civil conflict by focusing on the mediating role of ethnic identity. Using over 200 individual-level surveys from 89 countries, we provide a new data set with country- and group-level measures of inequality within and across ethnic groups. We then show that consistent with Esteban and Ray's (2011) argument about the need for labor and capital to fight civil wars, at both the country and group level, there is a strong positive association between within-group inequality and civil conflict. We do not, however, find support for previous arguments that inequality across ethnic groups should be associated with the incidence or intensity of civil conflict. By breaking down the measures of inequality into group-level components, the analysis helps explain why it is difficult to identify a relationship between general inequality and conflict. More generally, it highlights the limitations in cross-national research associated with drawing substantive conclusions by relying on measures of overall inequality, like the Gini.