Trilingual education and various curricula for third language acquisition have been increasingly implemented around the world in recent decades in order to meet the growing demand for plurilingualism. Key questions in immersion programmes are concerned with the ways in which plurilingual skills and strategies are related to communication and learning of the language registers in L1, L2 and L3, which are required for the learner to function successfully in institutional settings, and where these languages are being used for instruction of educational content (e.g., Cenoz, Hufeisen & Jessner, 2001). As a consequence, the new research area of trilingualism and third language acquisition has already established itself as a field of its ow...