Children in areas of deprivation are at increased risk for poor oral language development. A significant proportion of these children are dual language learners (DLL), which presents another challenge for practitioners. We ran an RCT to evaluate the efficacy of Talking Time©; an intervention designed to support early years’ practitioners to provide high quality interactions when engaging with children during activities using books and toys. We recruited 40 nursery settings from the lowest quintile for deprivation in London and the Northeast, half of whom were randomly allocated to the 16-week intervention. Baseline measures showed children’s language was below average. Data collection 7 months later showed the intervention had significantly impacted children’s expressive vocabulary for targeted items and DLL children had made significant progress on standardized measures of expressive and receptive language. Feedback from practitioners was overwhelmingly positive and the findings highlight the importance of providing structured, supportive training to enhance the quality of adult-child interactions in the early years.