This article discusses the prospects and challenges of energy cooperation between the European Union (EU) and Turkey within the context of the Eastern Partnership (EaP). Part of the EaP agenda is to advance energy cooperation between the EU and the partner states, particularly regarding the diversification of import routes. As an energy corridor between the EU and the hydrocarbon-rich Caspian states, Turkey is a strategic asset for European energy security. Turkey also has economic ties and political capital in the Caspian region that can help the EU reach out to its eastern partners. Despite robust incentives for cooperation, however, the EU-Turkey energy partnership has so far failed to meet mutual expectations. This article argues that this is primarily due to the inability of the two actors to credibly commit to regional energy cooperation. Commitment problem stems from two factors. First, the predominance of national energy interests over communal ones undermines credible commitment. The variation in energy needs of Member States prevents the EU from acting in unison in external energy policy. Similarly, Turkey also prioritizes its own energy security, particularly in its relations with suppliers, which undermines cooperation with the EU. Second, the EU and Turkey hold divergent perspectives on the potential political payoffs of energy cooperation. Turkish decision makers are convinced that energy cooperation warrants palpable progress in Turkey’s accession while most EU actors appear hesitant to establish a direct connection between energy and accession.