This Policy Insights examines the well-being of children from socio-economically disadvantaged backgrounds in comparison to their more advantaged peers. It shows that children from disadvantaged backgrounds are more likely to experience poor material outcomes, poor health, and worse education, as well as poorer social and emotional outcomes. These early well-being inequalities are rooted in the poorer environments that disadvantaged children face, making social inequalities in child well-being outcomes particularly difficult to address. There is a need for consistent support across all domains to address these challenges and improve the life experiences and outcomes of disadvantaged children.