Ideology is a constant in the Islamic Republic of Iran’s foreign policy, but the ideology itself has evolved in some areas and remained the same in others. This paper will examine the Shia-centric theocratic model espoused by Ayatollah Ruhollah Khomeini in the first decade of the revolution and its drive to export Iran’s revolutionary experience, which was followed by roughly fifteen years of relative pragmatic behavior that indicated a tempering of the ideological impulse. The paper will then review the ideological imperative behind Iranian foreign policy since 2005-2006, which is Eastward-looking and emphasizes Third World-ism. The final section of the paper will address the effect of the Arab Spring on Iran’s foreign policy and the implications for the future. Among the topics that will be addressed in this paper are factors that influence modern Iranian foreign policy, whether under a monarchy or a theocracy, including nationalism, exceptionalism, and entitlement, as well as the apparently more recent phenomenon of millenialism (Mahdism).