The effect of preschool vocabulary and grammar on early reading comprehension and word reading: A systematic review and meta-analysis

The oral language skills of vocabulary and grammar are associated with early reading ability, but how they relate to different aspects of reading - comprehension, word reading, and pseudoword reading - has not been systematically compared. A meta-analysis of 72 longitudinal studies (comprising 499 correlations from 23,387 children) examined the predictive relationship between vocabulary and grammar in preschool and reading comprehension, word reading, and pseudoword reading in children at the start of formal schooling. Preschool vocabulary and grammar each had significant, moderate effects on all aspects of early reading. This relationship was not moderated by the nature of the preschool oral language assessment (receptive vs expressive; complexity of response), nor by the time interval between preschool measures of oral language and school-aged measures of early reading. The age of the onset of formal schooling (used as a proxy for the start of formal reading instruction) moderated the size of the effect between preschool vocabulary and school-age word reading, revealing a greater impact for earlier formal schooling. Preschool vocabulary and grammar thus have a direct influence on all aspects of early reading, highlighting the benefit of early oral language support, particularly when reading instruction begins early in children's formal schooling.