Preschool attendance in the US is largely funded by parents, which means that the children of more affluent and educated parents are more likely to attend.  This column looks at the impact of Head Star, a large-scale preschool programme that serves roughly 1 million children annually in the US. The results show that children age-eligible for Head Start went on to achieve substantially higher levels of education. Head Start also led to improvements in adult economic self-sufficiency. Overall, the findings suggest that a large-scale preschool programme – even one with less per-child expenditures than model preschools – can deliver long-run benefits to students.