The Sunni Islamist terror organization known as the Islamic State, or ISIS, uses extreme violence and brutality against anyone it perceives as a threat to its goal of expansion and restoration of an Islamic Caliphate. The significant behavioral aspects of this unparalleled violence and its implications for the future are explored in a compelling Review article published in Violence and Gender, a peer-reviewed journal from Mary Ann Liebert, Inc., publishers. The article is available free on the Violence and Gender website until January 17, 2015.