This study investigated the relationships between children's linguistic environments and their language acquisition. Speech samples taken from seven firstborn children and their mothers when the children were i; 6 and 2; 3 were analysed within a number of semantic and syntactic categories to determine correlations between mothers' speech and subsequent language development. Several characteristics of mothers' speech (e.g. utterance length, use of pronouns) significantly predicted later child speech. The significant correlations suggested that mothers' choice of simple constructions facilitated language growth. Further, they showed that the motherese code differed from adult-adult speech in ways which aided language development. Differences between our study and previous investigations of environmental effects on language development probably resulted from the failure of earlier investigations to take into account children's level of language competence at the time when environmental effects were assessed. © 1979, Cambridge University Press. All rights reserved.
