This chapter examines the impact of oil and political economy on the international relations of the Middle East. It begins by discussing the relationship between oil and the consolidation and evolution of the modern Middle Eastern state system, noting that, while outside powers have invariably used oil in their calculations of Middle East policy, oil has figured less prominently in the foreign policies of Arab states. As regards domestic politics, the rentier state paradigm shows how oil has conditioned economic and political outcomes in both oil-rich and oil-poor states, slowing down the prospects for reform. The chapter proceeds by assessing the influence of oil on inter-Arab relations and concludes with some reflections on the regional and international environments as well as the political order in the Middle East.