The programme is funded by the UK Government, through UK Aid. Over the course of five years, EEG will commission rigorous research exploring the links between energy economic growth, and poverty reduction in low-income countries. This evidence will be specifically geared to meet the needs of decision makers and enable the development of large-scale energy systems that support sustainable, inclusive growth in low income countries in South Asia and Sub-Saharan Africa.The EEG Working Paper Series showcases the 18 State-of-Knowledge papers produced in Phase 1 of the EEG programme. These papers address gaps in knowledge and data in six critical themes related to energy and economic growth: the links between electricity supply and growth, finance and governance aspects, large scale renewables, sustainable urbanization and energy efficiency, the role of extractives, and design of energy systems. Cross-cutting themes of gender, climate change, and data are also addressed in dedicated papers.The views expressed in this paper do not necessarily reflect the UK Government's official policies. This paper is posted at the eScholarship Repository, University of California. Copyright © 2017 by the author(s). Abstract: countries dependent on oil and mineral exports are often advised to diversify their economies, yet surprisingly little is known about how this can be done. This paper reviews the recent literature on diversification in resource-dependent states and suggests it has been constrained by missing and inconsistent data, and a reliance on diversification measures that are relatively uninformative for resource-rich states. It then uses an improved measure of export concentration from Papageorgiou and Spatafora to document three empirical patterns over the last half-century: the divergence between oil-producing states and non-oil states; the reconcentration of exports in most oil and mineral producing states since 1998, caused by the boom in commodity prices; and the heterogeneity of the oil producers, marked by greater diversification in Latin America and Southeast Asia, mixed performances in the Middle East, and greater concentration in Africa and the former Soviet Union. While change in the former Soviet Union was spurred by large new discoveries, the diversification failure of all oilproducing states in both North and sub-Saharan Africa is striking, and stands in contrast to the region's non-oil producers. The paper concludes with a research agenda for deepening our understanding of this issue.