ABSTRACT This 5-year longitudinal case study contributes to our understanding of how family and space impact children’s bilingual identity construction and agency development. Participants are two French-English bilinguals from contrasting family profiles. Ava was born and raised in France. Her parents’ first language and her dominant home language is English. Victor was born in France. His parents’ first language and his dominant home language is French. His family moved to Australia for 3 years before returning to France when Victor was 5. Ava and Victor, who attend the same bilingual school programme in France, are followed from the beginning to the end of elementary school. Our results show that parents’ investment is critical to children’s attitudes and identity construction. While birthplace and family links to languages and cultures are highlighted, length of time spent in a place is also significant, although it impacts the children differently. Expressions of identity evolve constantly, as reinterpretations of children’s past and present experiences, together with the support of people around them, influence their plural self-concept and agency development.