For the past forty years, the relationship between the United States and Iran has been defined in terms of hostility and mutual suspicion. Unfortunately, many scholars have subscribed to this view in the past, which was the product of often oversimplified and far too generalized approaches to studying foreign policy. While most traditional analysis methods focus on a macro-level examination of decision making and the strategic behavior of a nation as a whole, this study proposes an alternative viewpoint. Individual actors play a central role in the decision-making and shaping of foreign policy. Therefore, evaluating their beliefs and perceptions about the external world is crucial to understanding foreign policy consequences manifesting in the interactions between nations. This study aims to thoroughly investigate the belief systems of the U.S. and Iranian leaders between 1953 and 2020 to assess the true nature of their relationship and each one's strategic motivations. The leading research questions addressed in this thesis are: What are the belief systems of the U.S. and Iranian leaders that drive the interactions between the two countries? What are some shared patterns among these leaders' beliefs, and how does each compare to the average leader? Are these results consistent with theoretical assumptions about their relationship? To answer the research questions, this work employs the quantitative Operational Code Analysis, which uses individual leaders' verbal material to determine their belief systems. The outcomes are then analyzed by performing a series of difference of means tests. Following their statistical preferences are assessed in accordance with the principles of Brams' (1994) Theory of Moves (TOM) and Theory of Inferences about Preferences (TIP). The results show that the representation of the U.S. and Iranian leaders' nature and motivations across conventional wisdom is not entirely accurate. Hence, reinforcing the value and significance of individual-oriented approaches to studying foreign policy.