Early childhood well-being is a multidimensional academic concept and research field focused on understanding and promoting the optimal physical, cognitive, social, and emotional development and health of children from birth through approximately eight years of age. It investigates the complex interplay of biological, environmental, and relational factors influencing a child's thriving, encompassing domains such as health status, safety, learning readiness, emotional regulation, and social competence within their family, community, and policy contexts. This concept is significant for identifying foundational determinants of lifelong health, learning, and societal contribution, thereby informing public health, education, and social policy interventions aimed at ensuring equitable developmental opportunities.