The book explores the prohibition and prosecution of hate speech in international law.  Building on the international legal framework, the invaluable jurisprudence of the Trial and Appeal Chambers of the UN ad hoc Tribunals (the ICTY and the ICTR), and views of scholars in the social sciences, the book focuses on two inter-related complexities in prosecuting hate speech in international criminal law: criminal participation and causation. A hypothetical scenario is developed, with numerous actors playing various roles in that given context, with the impact of altering their criminal liability, and raising further questions that touch on the issue of causation in criminal law.