After briefly reviewing the process of political development in Malaysia, we shall introduce the British decolonization policy after World War II. We then explore how the Malay Union was imposed in 1946 and transformed into the Federation of Malaya in 1948, which was merged with Singapore, Sabah, and Sarawak to become the Federation of Malaysia in 1963. In the following section, we examine why and how Singapore was allowed to join the Federation and forced to exist from it. Finally, we will conclude with the discussion of citizenship and the construction of the Malaysian nation-state.