This chapter develops a history of internal self-determination. It shows that internal self-determination, as an idea, has a long history; and that the internal dimension of self-determination has always been an essential part of the broader concept of self-determination. The chapter also argues that the construction of the internal–external dichotomy took place in the 1940s due to the intervention of the Netherlands, in the context of Indonesia's decolonization. The principle started to become popular during the Cold War. The Cold War's end resulted in a renewed interest in self-determination, with international lawyers starting to write about it. This history is critically narrated in this chapter.