Investment arbitration awards often give the impression that investment treaties are designed to reflect the interests of two actors: “investors” and “states”. There are in fact a myriad of actors, or “voices”, behind each word in an investment agreement. This chapter identifies three broad categories of voices: voices inside, outside and among states. It explores the range of voices that influence investment treaty text by reference to those three categories. The chapter ‘Voices That Shape Investment Treaties: Inside, Outside and Among States’ in European Yearbook of International Economic Law argues that modern investment treaties are multifaceted texts that are influenced by a range of voices from within and outside of government.