Multilingual identity, considered here as being shaped by learners evaluations, emotions and experiences relating to languages and language learning, has gained increasing attention among both researchers and practitioners. Indeed, school-based studies have not only suggested meaningful connections between learners’ multilingual identity and attainment but have also indicated the potential for an identity-based pedagogy to enhance students’ multilingual identity. However, much research to date has tended to focus on quantitative data at the level of a class or cohort. This paper, therefore, aims to qualitatively explore how adolescents develop their understandings of multilingualism and various dimensions of their own multilingual identity during an identity-based pedagogical intervention in the languages classroom. A qualitative approach was adopted drawing on interview data from 14 Year 9 (age 13–14) learners in secondary schools in England who participated in a year-long identity-based intervention in their languages lessons. The following three profiles of development were identified which capture students’ varied experiences of the intervention: resistant multilingual identity development, emergent multilingual identity development and reflexive multilingual identity development. We reflect on each of these in turn and highlight both theoretical and pedagogical implications for developing students’ multilingual identity in the classroom. [ABSTRACT FROM AUTHOR]