Oral language enrichment in preschool improves children's language skills: a cluster randomised controlled trial.

Background: Oral language skills provide the foundation for formal education, yet many children enter school with language weaknesses. This study evaluated the efficacy of a new language enrichment programme, the Nuffield Early Language Intervention-Preschool (NELI Preschool), delivered to children in the year before they enter formal education.

Methods: We conducted a preregistered cluster randomised controlled trial in 65 nursery schools in England (https://doi.