AbstractThis article considers the debate over the “resource curse” (i.e., whether too much natural-resource wealth is harmful for developing countries) along with the debate about the mechanisms and conditions that likely generate the reported problems. After reviewing the literature on the resource curse, this article discusses the ways that scholars define “natural resources.” It then analyzes research on how resource wealth affects democracy, the quality of government institutions, and the incidence of violent conflict. It cites evidence showing that petroleum wealth, in particular, seems to have at least three harmful effects: to make authoritarian regimes more durable, to increase certain types of corruption, and to foster the onset of violent conflict in low- and middle-income countries, particularly when this form of mineral wealth is found in the territory of marginalized ethnic groups.