Iranian foreign policy during the post-revolutionary period has often been described as pursuing ideological objectives and means. Given the problems usually associated with the concept of ideology, the alternative concept of “domestic ideational sources” would offer a broader perspective and prove less problematic. By this concept is meant the totality of ideas, norms, rules, and discourses that in their inter-relations make the material life meaningful. The basic conceptual and theoretical aspects of the role of ideas and domestic ideational sources in foreign policy - in general and with particular emphasis on the realist outlook – are discussed in the first part of the article. Based on this brief theoretical expose, the article will attempt to look into - and clarify – the main – Islamic- Shi’ite -- components of the domestic ideational sources of Iranian foreign policy since 1979. It will be argued that basic Islamic-Shi’ite ideas; the Iranian encounter with and experience of the West during the 19th and 20th centuries; Iranian intellectuals' response to the West's challenge manifested in a kind of Occidentalist discourse; and Western counter hegemonic, leftist and anti-imperialist discourses; have all played a role in shaping and/or affecting Iran’s Islamic revolutionary discourse. Furthermore, the discussion will also show how the discourse of the international system (or international ideational structure), have affected the Islamic discourse, which has led in turn to a variety of interpretations of domestic rules and norms. It will as well be argued that in the process of interaction some extra-religious ideas/discourses and events/experiences have influenced the formation of some versions of the Islamic discourse.