This study employs the Specificity Principle to examine the relative impacts of external (input quantity at home and at school, number of books and reading frequency at home, teachers' degree and experience, language usage, socioeconomic status) and internal factors (children's working memory, nonverbal intelligence, learning-related…

Data were analyzed from a population-based, longitudinal sample of 8,650 U.S. children to (a) identify factors associated with or predictive of oral vocabulary size at 24 months of age and (b) evaluate whether oral vocabulary size is uniquely predictive of academic and behavioral functioning at kindergarten entry. Children from higher…

Although the research literature regarding language growth trajectories is burgeoning, the shape and direction of English Language Learners' (ELLs) language growth trajectories are largely not known. This study used growth curve modeling to determine the shape of ELLs' language growth trajectories across 12,248 oral narrative language samples…

Executive control (EC) is related to mathematics performance in middle childhood. However, little is known regarding how EC and informal numeracy differentially support mathematics skill acquisition in preschoolers. A sample of preschoolers (115 girls, 113 boys), stratified by social risk, completed an EC task battery at 3 years, informal numeracy…

This study used the monozygotic (MZ) twin difference method to examine whether differences in friends' aggression increased the differences in MZ twins' aggression and depressive symptoms from kindergarten to Grade 1 and whether perceived victimization by the friend played a mediating role in this context. Participants were 223 MZ twin pairs.…

This study investigates the link between the frequency of family breakfasts and dinners and child academic and behavioral outcomes in a panel sample of 21,400 children aged 5-15. It complements previous work by examining younger and older children separately and by using information on a large number of controls and rigorous analytic methods to…

The effects of geographic variations in cost of living and family income on children's academic achievement and social competence in first grade (mean age = 86.9 months) were examined, mediated through material hardship, parental investments, family stress, and school resources. Using data from the Early Childhood Longitudinal Study-Kindergarten…

This longitudinal study examined different explanations for negative associations between aggression and academic achievement using data collected from 403 children from low-income families followed from kindergarten or first grade (ages 6 and 7 years) through fifth grade (ages 10-11 years). Most results of growth curve analyses examining change…