Individual language biographies have been associated to students’ and preservice teachers’ language awareness and willingness to engage in multilingual pedagogies. In this contribution, I analyse student teachers’ language biographies to understand how these social actors perceive their own development throughout the life span. Building on my previous distinction between latent and real Dominant Language Constellation (DLC), I describe how visual and written language autobiographies carry the traces of significant moments of linguistic ecological transitions, following Bronfenbrenner’s theory of human development. I argue that not all languages of the latent DLC integrate the real DLC and that those moments of transition are important to explain internal changes in an individual’s DLC across their lifespan. Focusing on language autobiographies of student teachers of French in Germany, I identify three moments of linguistic ecological transitions that are represented as impacting their DLC: starting to learn particular languages at school, emigrating as an adult (and having to adapt to a new schooling and professional environment), and studying and working abroad for a (limited) period of time. Following a content and multimodal analysis of the written and visual language narratives, I show that: (i) none of these moments has a uniform impact on student teachers’ DLC; and (ii) the sustainable development and maintenance of student teachers’ DLC is not achieved through the juxtaposition of single moments of linguistic transition, but rather through the dynamics and relationships that characterize them. In the conclusion, I advance the idea that the DLC approach contributes to a more holistic, emic, and individual-based explanation of multilingualism as lived, in what could be an innovative model of multilingualism.