Background: A significant number of children now enter formal education in England with reduced levels of proficiency in oral language. Children who come from disadvantaged backgrounds and who are English language learners (ELL) are at risk of limited oral language skills in English which impacts on later educational achievement. Aims: This paper reports the development of a theoretically motivated oral language intervention, "Talking Time," designed to meet the needs of preschool children with poor language skills in typical preschool provision. Sample: One hundred and forty-two 4-year-old children attending three inner city preschools in a disadvantaged area of London, England. Method: This is a quasi-experimental intervention study comparing children exposed to "Talking Time" with children exposed to a contrast intervention and children receiving the statutory early years curriculum. Measures were taken of both targeted and non-targeted language and cognitive skills. Results: Data were analysed for the ELL. The intervention had a significant effect on vocabulary, oral comprehension, and sentence repetition but not narrative skills. As predicted, there were no effects on the skills which were not targeted. Conclusions: Regular evidence-based oral language interactions can make significant improvements in children's oral language. There is a need to examine the efficacy of more intensive interventions to raise language skills to allow learners to access the curriculum.