The way to interact with Iran has always been a controversial issue in transatlantic relations. The American and European positions towards Iran has witnessed many ups and downs in the past three decades and based on different developments, both sides have had different stances. The main question of this article is that" what has been the dominant model in the transatlantic positions regarding Iran in the past three decades"? Comparing American and European positions' towards Iran, the level of convergence and divergence of these actors will be scrutinized. Our findings indicate that the trend of transatlantic positions could be divided in to three stages. In the first stage which starts from the victory of the Islamic Revolution till the collapse of the Soviet Union and the end of the Cold War, the United States and the European countries share common concerns and try to contain the Revolutionary Iran. The second stage is coincided with some major international developments such as the end of Cold War, the Persian Gulf War (1991) and Iran's domestic developments including the end of imposed war and Hashemi Rafsanjani's presidency. In this period, there could be seen apparent gaps and differences in transatlantic policies. The third stage, up on which we mainly focus, begins with the introduction of Iran's nuclear file and the American attempts to convince the Europeans to limit and to contain Iran's nuclear program which finally led to a sharp convergence in these countries' positions. What is of great significance in this stage is a shift in European Union's policies (negotiation and interaction) in comparison with those of America's Approach (imposing sanctions and containment).