Research Findings: Data on more than 900 children participating in the National Institute of Child Health and Human Development Study of Early Child Care were analyzed to examine the effect of age of entry to kindergarten on children's functioning in early elementary school. Children's academic achievement and socioemotional development were measured repeatedly from the age of 54 months through 3rd grade. With family background factors and experience in child care in the first 54 months of life controlled, hierarchical linear modeling (growth curve) analysis revealed that children who entered kindergarten at younger ages had higher (estimated) scores in kindergarten on the Woodcock—Johnson (W-J) Letter-Word Recognition subtest but received lower ratings from kindergarten teachers on Language and Literacy and Mathematical Thinking scales. Furthermore, children who entered kindergarten at older ages evinced greater increases over time on 4 W-J subtests (i.e., Letter-Word Recognition, Applied Problems, Memory for Sentences, Picture Vocabulary) and outperformed children who started kindergarten at younger ages on 2 W-J subtests in 3rd grade (i.e., Applied Problems, Picture Vocabulary). Age of entry proved unrelated to socioemotional functioning.
Practice: The fact that age-of-entry effects were small in magnitude and dwarfed by other aspects of children's family and child care experiences suggests that age at starting school should not be regarded as a major determinant of children's school achievement, but that it may merit consideration in context with other probably more important factors (e.g., child's behavior and abilities).