In 1957, when the Treaty of Rome was signed, founding the European Economic Community (EEC), which later became the European Union (EU), four out of six of the original member states were colonial powers. This article uses archival material from the Treaty of Rome negotiations to interrogate ways in which the colonial politics of the time shaped the drafting of legal categories describing individuals: those of peoples, inhabitants and workers. As the Treaty of Rome ‘associated’ colonized territories to the EEC, this article shows how the treaty simultaneously arranged its legal categories to exclude individuals who lived in colonized territories from legal benefits and representation. This article situates the EU as an example of a post-World War II international organization, with its founding legal texts shaped by colonialism.