This expanded and revised edition of "The Strategic Culture of the Islamic Republic of Iran," first published by Marine Corps University in 2011, sharpens, fleshes out, and updates analyses and arguments presented in the original edition. In the wake of the nuclear deal between the P5+1/EU and Iran (known formally as the Joint Comprehensive Plan of Action), and in light of the Islamic Republic's growing role in the Middle East, the need for such a publication is greater than ever before. It is my hope that this monograph will fill the need for a primer on the strategic culture of the Islamic Republic of Iran (IRI) that will provide insights into the factors shaping its regional conduct. Analysts, strategists, and policymakers are told to never "mirror image" when considering the conduct of another country, but they are never told what "image" to put in its place. This publication constitutes an attempt to convey the essential elements of the strategic culture of the IRI to assist these respective communities create an alternative image of "the other." It also represents an attempt to inject culture into the debate about strategy and policy. After more than a decade of combat in Afghanistan and Iraq, the US military understands very well the importance of factoring culture into tactical and operational planning. But there are few signs of a similar recognition of the importance of cultural understanding among planners and policymakers at the strategic and national levels.