The Islamic Revolutionary Guard Corps (IRGC) has been the subject of intense scholarly debate, as it has come to play an increasingly important role in the Islamic Republic of Iran at home and abroad. This chapter seeks to add to the literature on the IRGC by focusing on its role in Iranian domestic politics and foreign policy. The IRGC in domestic politics plays both a formal role as a security actor entrusted to "guard the revolution and its achievements", and an informal role as a patron of the principlist political current in electoral politics. The IRGC in foreign policy, shaped by its experiences in the Iran-Iraq War and characteristics as a military actor, emphasizes self-reliance, military power, and zero-sum confrontation. It participates in conducting foreign policy as both the main military force responsible for Iranian power projection abroad and the actor implementing much of the country’s Middle East policy.