Abstract
Children's oral language and self‐regulation skills are critical for healthy development and life trajectories. ENRICH is a preventive intervention developed for early childhood teachers to enhance these skills in toddlers. Kia Tīmata Pai (Best Start study) is a longitudinal cluster randomized controlled trial in 136 New Zealand early childhood education centers testing the impact of ENRICH with 1875 teachers on 1481 toddlers’ (M = 20.6 months at recruitment; 72% European, 24% Māori, 23% Asian, 9% Pacific using a total response method; 7% low‐SES, 40% middle‐SES, 53% high‐SES) oral language and self‐regulation skills. After 18 months, ENRICH produced benefits for children's oral language and self‐regulation skills (parent and teacher ratings) and for early literacy and social skills (teacher ratings) compared to an active control condition. Oral language benefits (parent ratings) emerged earlier for children from low‐ and mid‐socioeconomic (SES) families and whose mothers had lower educational qualifications. Benefits for oral language and self‐regulation skills at age 3 held regardless of children's SES, ethnicity, bilingual status, initial language level, age, and maternal education. Benefits for oral language at age 3 were moderated by child sex and differed by informant, with teachers perceiving greater ENRICH benefits for boys, and parents for girls. The likely mechanism of ENRICH's effects is through sensitive serve‐and‐return interactions that support children's oral language and attention skills. ENRICH is a potentially powerful tool for supporting toddlers’ language, cognitive, and socioemotional development with possible downstream effects for academic achievement, health, and well‐being. A video abstract of this article can be viewed at https://youtu.be/iIV1l0‐cKIo.