IMPORTANCE: Since 2001, the American Academy of Pediatrics has recommended universal developmental screening and surveillance to promote early diagnosis and intervention and to improve the outcomes of children with developmental delays and disabilities. OBJECTIVE: To examine the current prevalence and variation of developmental screening and surveillance of children by various sociodemographic, enabling, and health characteristics. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional analysis of the Health Resources and Services Administration’s 2016 National Survey of Children’s Health—a nationally representative survey of US children completed between June 2016 and February 2017—examined 5668 randomly selected children 9 through 35 months of age whose parent or caregiver responded to the address-based survey by mail or via a website. All analyses were weighted to account for the probability of selection and nonresponse and to reflect population counts of all noninstitutionalized US children residing in housing units. MAIN OUTCOMES AND MEASURES: Developmental screening was measured through a validated set of 3 items indicating receipt in the past year of parent-completed screening from a health care professional with age-appropriate content regarding language development and social behavior. Surveillance was determined by an item capturing verbal elicitation of developmental concerns by a health care professional. RESULTS: Of the estimated 9.0 million children aged 9 through 35 months, an estimated 30.4% (95% CI, 28.0%-33.0%) were reported by their parent or guardian to have received a parent-completed developmental screening and 37.1% (95% CI, 34.4%-39.8%) were reported to have received developmental surveillance from a health care professional in the past year. Characteristics associated with screening and/or surveillance that remained significant after adjustment included primary household language, family structure, household education, income, medical home, past-year preventive visit, child health status, and special health care needs. Having health care that meets medical home criteria was significantly associated with both developmental screening (adjusted rate ratio, 1.34; 95% CI, 1.13-1.57) and surveillance (adjusted rate ratio, 1.24; 95% CI, 1.08-1.42), representing an 8 to 9 absolute percentage point increase. State-level differences spanned 40 percentage points for screening (17.2% in Mississippi and 58.8% in Oregon) and surveillance (19.1% in Mississippi and 60.8% in Oregon), with approximately 90% of variation not explained by child and family characteristics. CONCLUSIONS AND RELEVANCE: Despite more than a decade of initiatives, rates of developmental screening and surveillance remain low. However, state-level variation indicates continued potential for improvement. Systems-level quality improvement efforts, building on the medical home, will be necessary to achieve recommended screening and surveillance goals.