This paper presents the concept of a “mandatory translation language” (MTL). Mandatory translation languages are languages whose speakers do not have (or cannor exercise) the right to receive translations into their language of the acts of others. Furthermore the paper examines a specific instance of the phenomenon (the Catalan language in Spain as an example of partial MTL). Finally it relates MLT to the concept of “linguistic security” – the extent to which individuals can live through their own language without being subject to pressure to use another. The research framework within which this paper is written is the study of the linguistic rights of members of linguistic minorities from a translation perspective.