International arbitral tribunals increasingly deal with cases in which the conduct of State entities enjoying separate legal personality harmed foreign investors. The book discusses the attribution of conduct of such entities in international investment law. Their conduct is, opposed to the conduct of actual State organs, not automatically attributable to the State, but only when the requirements of a specific rule of attribution are met. The author analyses these rules of attribution under public international law with the help of the ILC Articles on State Responsibility. Based on this analysis, the author examines the application of these rules in the jurisprudence of investment arbitration. Previous jurisprudence in this field has been relatively inhomogeneous and often lacked a sufficient distinguishing between the different rules of attribution. Concluding, the author argues in favour of strictly distinguishing between the rules and relying on the ILC Articles.