This chapter discusses how a Dominant Language Constellation approach to teaching and learning languages can be highly beneficial in diverse learning contexts in which languages that are brought to school by pupils coexist with curricula languages. A Dominant Language Constellation approach to teaching and learning languages is described in this chapter as the development of the awareness of the most expedient languages of a learner (Aronin 2016), and also as the actual pedagogical use of these languages for learning. During the 5-month period covered by the study conducted in a primary school in Barcelona, pupils created story books in English which were then translated into pupils' own languages. Pupils became aware of their Dominant Language Constellations by using translation and employed their own languages for learning English. Data analysis uncovers positive effects on pupils' motivation and attitudes towards languages and learning languages, a significant increase in language awareness among pupils and a positive impact on the teacher's plurilingual approach to teaching languages. [For the complete volume, "Dominant Language Constellations Approach in Education and Language Acquisition. Educational Linguistics. Volume 51," see ED660754.]