Speech and language delays affect 6-7% of children at school entry and can result in problems in one or more areas, such as understanding vocabulary and grammar, inferring meaning, expressive language, sound production, voice, fluency and articulation, and the use of language in social contexts.1 For some children, language problems are markers for—and secondary to—conditions such as autism, sensory impairment, or more general developmental disabilities. For others, they are the result of primary delay that cannot be accounted for by low non-verbal ability, hearing impairment, behaviour problems, emotional problems, or neurological impairments. Environmental factors such as limited opportunities for learning language or learning English as an additional language may also overlap with primary and secondary delay. In the linked cluster randomised trial (doi:10.1136/bmj.d4741), Wake and colleagues assess the effects of a low intensity parent-toddler language promotion programme delivered to toddlers identified as slow to talk on screening in universal services.2

Language delay that persists until school entry can have adverse effects on literacy, behaviour, social development, and mental health into adulthood, with receptive language and secondary delay particular risk factors.3 4 5 6 But the case …