A Cluster Randomized Controlled Trial Comparing the Efficacy of Pre‐School Language Interventions—Building Early Sentences Therapy and an Adapted Derbyshire Language Scheme

What is already known on the subject Early language development sets the stage for children's educational and psychosocial development and their life chances into adulthood. Early language interventions can be effective; however, there is a need to develop and evaluate early interventions which bring large effects and which can be delivered within the constrained resources of early years provision. Usage-based linguistics have not been explicitly applied to the design of early language interventions. There is evidence that the Derbyshire Language Scheme (DLS) promotes positive outcomes in comprehension abilities and BEST in production. What this paper adds to the existing knowledge Findings from a cluster-randomized controlled trial demonstrate that BEST, an 8-week, 15-min, small-group intervention, delivered twice weekly can produce moderate to high effects in expressive language outcomes for 3-4-year-old children with low language. A-DLS and BEST bring similar gains in comprehension standard scores but BEST leads to larger and more sustained progress in expression. Faster progress after intervention for BEST supports the hypothesis that it promotes the development of abstract representations of predicate-argument structures, supporting generalization and accelerating language learning. What are the potential or actual clinical implications of this work? BEST, a low-dosage, manualized intervention delivered with high fidelity can be effective for children from a range of socio-economic backgrounds bringing moderate to high effects. Effective and efficient intervention can be delivered through the precise manipulation of active ingredients within intervention sessions (in this case, the cognitive mechanisms hypothesized to promote language learning and abstract knowledge in usage-based theory).