• Article

Age of peers and early childhood development

We examined the developmental trajectories of 59 children between 21 and 67 months of age randomly assigned to same-age or mixed-age child care groups. Children were assessed at 6-month intervals with the Battelle Developmental Inventory. Using a hierarchical linear model for analysis, we computed individual and group growth curves for overall development and development within 5 domains: communication, cognitive, motor, adaptive, and personal-social. Group assignment affected the developmental trajectories for communication, cognitive, motor, and overall development, with mixed-age children showing a quadratic trajectory and same-age children a linear trajectory. For adaptive and personal-social development, however, the trajectories were similar. Across all domains, the mixed-age children tended to score higher than the same-age children at the younger ages, but these average differences decreased over time and had disappeared by age 5 years


Bailey, D., Burchinal, MR., & McWilliam, RA. (1993). Age of peers and early childhood development. Child Development, 64(3), 848-862. https://doi.org/10.1111/j.1467-8624.1993.tb02947.x