Language law in Belgium is based on two concepts. The territoriality principle entails that official language use varies from one linguistic region to another. The constitutional freedom of language is an essential complement to territoriality and grants residents the right to use the language of their choice. In the monolingual regions of the country, this fundamental right is, however, limited to the private domain. In the bilingual region of Brussels-Capital, a freedom of language, limited to French and Dutch, exists also in the public domain: residents may choose either language to communicate with the authorities. In this paper, it is explained how the Belgian language regime came about as a result of the interaction between territoriality and freedom of language, already dating back to long before Belgium came into existence. It is argued that the Belgian model has, in actual fact, served as a tool for peaceful conflict management and has greatly contributed to maintaining language diversity. Yet, at the same time, tensions between the two basic concepts exist and are highlighted in this paper.