Abstract Background New Mexico is the first state in the U.S. to implement a comprehensive, statewide assessment of children’s developmental health in tandem with sweeping early childhood policy reforms. These reforms—including universal child care and preschool—aim to strengthen the early childhood ecosystem and improve population health. Yet, little is known about the developmental health of kindergarteners in the state or how demographic and neighborhood contexts shape readiness at school entry. This study provides the first population-level snapshot of developmental health among New Mexico’s kindergarteners during a period of significant policy transformation. Methods We conducted a statewide cross-sectional study of kindergarteners assessed from April to May 2024. Data represents 116 school districts, 441 schools, 600 neighborhoods, and 1,380 classrooms ( N = 18,974 children). Children’s developmental health and school readiness was measured using the Early Development Instrument (EDI), which assesses five domains: physical health and well-being, social competence, emotional maturity, language and cognitive development, and communication skills and general knowledge. Neighborhood context was assessed using the National Neighborhood Equity Index (NNEI), which classifies neighborhoods into four levels (zero, low, medium, high inequity). Descriptive statistics were used to examine child characteristics, developmental outcomes, and neighborhood patterns. Multilevel regression models examined associations between EDI outcomes and child characteristics (sex, ethnorace, English Language Learner ELL status, and Individualized Education Program IEP status) and neighborhood context (NNEI). Results Children had a mean age of 6.21 years with a 0.33 standard deviation, and 51% were boys. More than 70% of kindergarteners were overall on-track in developmental expectations across individual domains; however, fewer than 48% met expectations across all five domains simultaneously. Vulnerabilities were more pronounced among boys, African American/Black and American Indian/Alaska Native children, ELLs, and students with an IEP. 61% of children resided in neighborhoods with zero or low equity barriers. A clear social gradient was observed, with 23% of children in neighborhoods with NNEI level ‘zero’ demonstrated overall vulnerability in ≥ 1 domain, compared with 33% of children in neighborhoods with NNEI level ‘high.’ Conclusions Findings indicate generally positive developmental health among New Mexico kindergarteners, yet significant disparities persist across demographic and neighborhood lines. The integration of bold policy reforms with a statewide developmental assessment represents a promising model for monitoring population health and identifying opportunities for targeted early childhood prevention and early intervention supports.
Perrigo et al. (2026) studied this question.