A few years after Turkey and Iran appeared to be growing closer, the pendulum has swung back and the two sides are increasingly at odds. The turmoil in Syria has brought the long-term competition between Ankara and Tehran for regional influence to the fore. Iran has doubled down on its wager that the current regime in Damascus can weather the storm, while Turkey is betting that a post-Assad Syria would be more closely aligned with its own regional interests. But despite significant differences and growing antagonism, over Syria and more broadly, Turkey and Iran still have substantial reasons to cooperate. These include mutual interests in dealing with restive Kurdish populations and robust trade, particularly Turkey’s reliance on Iranian oil and gas. History suggests that Ankara and Damascus will find ways to manage tensions, so the rivalry for regional influence is more likely to simmer than boil over into outright conflict. The Turkish-Iranian relationship will continue to resist simplistic caricatures.