We examine the role of political fractionalization in understanding the “resource curse”. Using panel data for 30 oil-rich countries, we find that the income effect of resource rents is moderated by the political power balance. With a strong government, resource wealth can generate growth even in an environment of poorly developed institutions, while adding oil revenues to a weak government may have damaging effects on the economy. These results have important implications for the economic prospects of the oil-rich countries in the Middle East, which are currently undergoing profound political changes.