Prior research shows that establishing early literacy and numeracy skills may help children achieve better outcomes in later schooling. Data from the Regional Project on Child Development Indicators (PRIDI), which focused on Costa Rica, Nicaragua, Paraguay, and Peru, provided insights into four domains of child development that build the foundation for future learning outcomes: cognition, language and communication, socioemotional development, and motor skills. This brief presents results from in-depth analysis using data from Trends in International Mathematics and Science Study (TIMSS) and Progress in International Reading Literacy Study (PIRLS), which demonstrate that social inequalities and their relationship to learning outcomes commence in early childhood. The authors explored: (1) the engagement in early literacy activities of parents from different educational backgrounds; (2) the relationship between this engagement and later student achievement in primary school for children from diverse socioeconomic backgrounds; and (3) the relationship between children's attendance of institutional early childhood provision and parents' educational background. Results suggest that early learning activities have some effect on student achievement in later schooling. Further, in some education systems, parental engagement with children on stimulating learning activities is unequal across families from different educational backgrounds. Also, children from socially disadvantaged backgrounds tend to experience less stimulating educational activities at home and have poorer access to institutional early childhood provision.