Vocabulary, comprehension and retelling in multilingual children: age and input tell the whole story

Heritage languages (HL) are spoken in most households, yet developmental trajectories beyond vocabulary are mostly represented by monolingual children. We tested 53 4-year-olds (26 HL multilingual from heterogeneous ethnicities, 27 monolinguals, 29 females) on English receptive vocabulary and oral discourse skills (story comprehension and retelling). Using Bayesian modelling we found that age and amount of English input predicted vocabulary, comprehension, and retelling skills, with monolingual children exhibiting an age-sensitive advantage in receptive vocabulary and retelling but not in comprehension. Multilingual children demonstrated comparable linguistic skills to those of monolingual peers, even when mostly exposed to their HL. Crucially, increments in English input with age led to monolingual-like proficiency in multilingual children. We discuss the implications of our findings for children’s lifespan multilingualism.