Head Start is a US Federally funded program that was created in 1965 to help children from disadvantaged backgrounds prepare for school. Some studies have suggested that the impact of participation disappears after just a few years.

Researchers at the University of Oslo have published a study that found significant longer term impacts. Looking at a cohort of 30 year-olds, they found that "... Head Start increases high school graduation by at least 4 percentage points and the probability of earning more than the (one-person) poverty threshold by at least 6 percentage points." Interestingly, this impact was concentrated at the bottom end of the distribution, and among women, Blacks and Hispanics.

Bottom-line: With respect to years of educational achievement and earnings, Head Start provides significant benefits, especially to participants from the most disadvantaged households.