The chapter surveys crimes against humanity and genocide in the conflict. The authors provide a legal conceptual analysis of the two different international crimes – which share common features distinguishing them from ordinary crimes and yet are also legally distinguished from each other. Moodrick-Even Khen and Siman focus on specific conduct that form two of the most documented crimes in the Syrian conflict: the crimes against humanity of torture and extermination of prisoners in detention facilities of the Syrian government; and the genocide of the Yazidis committed by ISIS. The legal analysis is used to explain who, among the various parties to the conflict in Syria, is responsible for each crime and the justifications for the allegations against each party.