Ensuring the well-being of the 73 million children in the United States is critical for improving the nation's health and influencing children's long-term outcomes as they grow into adults. OBJECTIVE To examine recent trends in children's health-related measures, including significant changes between 2019 and 2020 that might be attributed to the COVID-19 pandemic. DESIGN, SETTING, AND PARTICIPANTS Annual data were examined from the National Survey of Children's Health (2016-2020), a population-based, nationally representative survey of randomly selected children. Participants were children from birth to age 17 years living in noninstitution settings in all 50 states and the District of Columbia whose parent or caregiver responded to an address-based survey by mail or web. Weighted prevalence estimates account for probability of selection and nonresponse. Adjusted logistic regression models tested for significant trends over time.MAIN OUTCOMES AND MEASURES Diverse measures pertaining to children's current health conditions, positive health behaviors, health care access and utilization, and family well-being and stressors.