Intro: Federal and state governments spend ∼$37 billion annually on early childhood programs, and researchers are interested in more systematically assessing their benefits with respect to numeracy/literacy as well as to social/emotional development of young children. Toward this objective, the 2016 National Survey of Children’s Health (NSCH) introduced a new derived measure -- “Healthy and Ready to Learn” -- a composite of 10 pre-academic readiness skill items (PARS) and 11 social/emotional development (SED) items. This new measure is a Title V MCH Services Block Grant National Outcome Measure, though its scoring criteria are still being developed and not yet been made public. While experts explore how to best refine these 21 items into a reliable and valid outcome measure, the recent release of the NSCH data provides an opportunity to examine differences in PARS and SED between children who do and do not attend preschool. Objective: To assess and compare the PARS and SED of healthy children ages 3-5 who attend preschool with those who do not attend preschool. Methods: Responses to the 21 items that comprise the new “Healthy and Ready to Learn” measure were assessed for healthy/well children. Children were excluded from the analysis if they had a “special healthcare need” or if they were currently receiving early intervention or special education, developmental therapies (OT, PT, S-L Therapy) or behavior therapy. Logistic regressions, adjusted for age, sex, race/ethnicity, prematurity, household structure, household income, parent employment, and highest household education, were performed for each of the PARS and SED items to compare the school readiness of children in the two groups. In addition to item analyses, a regression was done to compare the percent of children who met all (or all but 1 or 2) of the PARS and SED criteria. Results: The final sample consisted of 2,539 children ages 3-5 not in preschool and 3,438 children who attend preschool. Table 1 provides a summary of the sample characteristics of the children and their parents/household. Table 2 summarizes the weighted proportion of children in each group who met the defined criteria for each item. With respect to PARS, children who attend preschool out-performed the comparison group on 7 of the 10 PARS items and also did better on all 3 composite measures. By contrast, children who attend preschool only did better on 3 of the 11 SED items, and there were no differences on the 3 composite measures. Conclusion: Analysis of a large, nationally representative sample of children ages 3-5 suggests that preschool programs in the US have a substantial impact on the literacy/numeracy skills and some benefit with respect to social/emotional development.