There are large gaps by SES at school entry, which persist, and in some domains widen, over childrenтАЩs school careers. By kindergarten entry, there is a significant gap in reading and math (1 SD) between children from very low-income families (i.e., family income in the bottom 20 percent of the distribution for the sample) and those from very high-income families (i.e., family income in the top 20 percent of the distribution). Children from very low-income families are also behind (.5 of a SD) children from middle-income families (e.g., family income in the middle 20 percent of the distribution), though less so. Although much smaller, there are also differences by family income in teacher-reported externalizing problem behaviors at kindergarten entry.┬а Children from very low-income families are slightly behind (.25 of a SD) their counterparts from very high-income families. This gap persists through fifth grade (with poor children continuing to demonstrate significantly more behavior problems).
Like family income, parentsтАЩ education is also a factor in the achievement gap. At 24 months, there is a sizeable gap in cognitive skills (nearly .9 of a SD) between children whose mothers have a BachelorтАЩs degree, and children whose mothers have less than a high school degree. By age five, there is a large gap in reading and math skills (1 SD) for children whose parents have less than a high school degree compared to a B.A. or higher. This gap persists through age 14. Overall, achievement gaps by family income and education are large by the time children begin formal schooling (i.e., at kindergarten entry), and change very little beyond elementary school.