Since the 1979 Iranian Revolution, mainstream analysis of Iranian foreign policy has failed to consider the preceding history – particularly in the past couple decades. Across governments, intelligence agencies, militaries, think-tanks, and more, the general view is that problematic Iranian activity in the region began in 1979, thereby offering a troubling implication that should the Islamist regime be changed – either domestically or via external pressure – these issues will disappear. This thesis seeks to push back against this view and argues that in the context of an international system dominated by the United States, Iran can be seen as a state with an imperially expansionist national identity that has channeled hegemonic pursuit in the Greater Middle East, advancing them through revisionist and irredentist means. Furthermore, Iran has been pursuing these hegemonic aspirations prior under both the Pahlavi monarchy and the Islamic Republic. This thesis posits that there are four foreign policy principles observable in Iranian behavior that provide a line of continuity between the Pahlavi regime and the Islamic Republic, casting doubt on the notion that should the Islamist regime collapse these lines would be severed; they have survived far more traumatic events. The foreign policy of the United States would benefit greatly from understanding the history of Iran, and how its imperial memory, experience with Islam, and ascendancy during the Cold War all contribute to its contemporary behavior. This thesis addresses each of these components, along with an in-depth study of how this line of continuity between regimes is manifested in the Persian Gulf. Lastly, there are policy recommendations and analysis made in the concluding chapter which address what role, if any, the United States – and other external actors – can play in promoting positive change in Iran and the region.