This chapter focuses on the crime of genocide. The prohibition against genocide is now found in treaty and customary law, and is universally accepted as being an international crime ‘whether committed in time of peace or in time of war’. Genocide requires that a prohibited act is committed against a member of one of the protected groups, being a ‘national, ethnical, racial, or religious group’. The chapter first considers the definition of the protected groups. It then outlines the legal definitions of the prohibited acts; considers whether there is a ‘contextual element’ required as part of the crime of genocide; and examines the mental element of the crime of genocide and the role of the ‘special intent’ requirement.