With increased linguistic diversity in schools, it is paramount that initial teacher education and training (ITET) develops linguistically responsive teachers who can confidently work in the complex language ecologies characterising today's multilingual classrooms. We argue that to achieve this aim, all future teachers should be given opportunities to reflect on and appreciate their multilingual repertoires during ITET. Accordingly, we present the findings of a quasi-experimental study exploring the extent to which a group of pre-service teachers expressed a multilingual identity before and after participating in an innovative, identity-oriented online intervention. Participants were 37 primary and secondary pre-service teachers enrolled on an ITET course in England. During their training, 17 pre-service teachers participated in the intervention, whilst a control group of 20 did not. All participants completed a questionnaire before and after the intervention. A comparison of pretest-posttest responses revealed statistically significant increases in scores on various items designed to capture participants' multilingual identities in the experimental group with medium-to-large effect sizes, and no significant differences in the control group. Qualitative data from post-intervention interviews corroborated the overall finding that, after the intervention, pre-service teachers tended not only to consider themselves more multilingual, but also express a non-prescriptive view of multilingualism.