The first five years of a child's life is a period of great opportunity, and risk. The cognitive and social-emotional skills that children develop in these early years have long-lasting impacts on their later outcomes throughout schooling and adulthood. The International Early Learning and Child Well-Being Study was designed to help countries assess their children's skills and development, to understand how these relate to children's early learning experiences and well-being. The study provides countries with comparative data on children's early skills to assist countries to better identify factors that promote or hinder children's early learning. Three countries participated in this study in 2018: England (United Kingdom), Estonia and the United States. The study directly assessed the emergent literacy and numeracy, self-regulation and social-emotional skills of a representative sample of five-year-old children in registered school and ECEC settings in each participating country. It also collected contextual and assessment information from the children's parents and teachers. This report sets out the findings from the study as a whole.