Turkish-Iranian relations have flourished parallel to Ankara's reorientation toward the Middle East. Two highly-publicized developments underscore how Iran has grown in importance for Turkish foreign policy. Turkish Prime Minister Recep Tayyip Erdogan's objections to harsher Western responses to the Iranian nuclear program, and the warm welcome the Iranian leader Mahmoud Ahmedinejad continues to receive from the Turkish leaders are taken as indications of changing priorities of Turkey's Middle East policy. Turkey's growing divergence from the transatlantic agenda on such issues raises an interesting question: what drives the rapidly evolving cooperation between Ankara and Tehran? Can this change be explained by reference to the identity of Turkey's incumbent Justice and Development Party (JDP)? The paper questions identity-based explanations of Turkey's policy towards Iran under the rule of the JDP, and proposes instead the examination of the Turkish-Iranian relations from the 'energy cooperation' angle. By locating this case against the background of Turkey's dependence on imported hydrocarbons and its ambitions to assert its role as an energy transportation corridor, the paper traces how energy cooperation plays a major role in the deepening cooperation between Turkey and Iran. In 2009 alone, the JDP government pursued aggressive energy diplomacy, and signed various energy deals with Middle Eastern countries, especially Iran, Syria, Qatar, and Iraq. The most spectacular among these was a Turkish-Iranian deal on joint exploitation of Iranian natural gas reserves, and the export of Iranian gas to European markets via the planned Nabucco pipeline that crosses the Turkish territory. Contrary to the American position on Iran, Turkish government's insistence to integrate Iran into the Nabucco demonstrates the extent to which it is determined to play a more independent role in energy geopolitics, even at the expense of risking Turkey's ties with the West. Based on this case study, the paper puts forth two interrelated arguments: First, an identity-based explanation of Turkish foreign policy fails to fully account Turkey's recent activism in the Middle East. Second, Turkey's new foreign-policy agenda can be better comprehended if one considers it against the background of interest-driven factors, especially the growing role of energy geopolitics in shaping Turkey's foreign affairs. The paper concludes that the case of Turkish-Iranian relations is largely explained by considerations of national interests, as the recent energy agreements spearheaded by the Turkish government correlate with its aspirations to play a central role in regional and global politics.