The detailed age trajectory of oral vocabulary knowledge: differences by class and race

Data from the Children of the NLSY79 (CNLSY) are pooled together across survey waves, 1986–2000, to provide an unusually large sample size, as well as two or more observations at different time points for many children, recorded at single months of age between 36 and 156 months. We fit a variety of multilevel growth models to these data. We find that by 36 months of age, large net social class and Black–White vocabulary knowledge gaps have...