Led by Professors Stephanie Jones and Nonie Lesaux, the Early Learning Study at Harvard (ELS@H), a cornerstone of the Zaentz Early Education Initiative (https://zaentz.gse.harvard.edu/), is a first-of-its-kind, statewide study designed to examine children's learning and development in the context of their early education and care experiences. ELS@H's large-scale, longitudinal design and its population-based, representative sample enables the study to address key questions that face today's policymakers and practitioners, focusing in particular on questions about scaling effective models and practices, and about the characteristics of settings and communities that are essential for children's long-term health and well-being. ELS@H draws on successes in the design of medical and public health research to examine the relationship between children's development in several domains--language, cognition, social-emotional, neuro-physiology--and the nature and quality of their early learning environments (e.g., degree of stress, language-learning opportunities) across the Commonwealth of Massachusetts. Importantly, ELS@H focuses on all types of early education and care settings including both formal and informal settings. The study addresses primarily descriptive questions that existing research, which is typically focused on only one domain of early development, often located in just one site or community, and typically only one type of care or education setting, has not. (author abstract)