Is preschool worth it? Policymakers, parents, researchers and us, at NPR Ed, have spent a lot of time thinking about this question.

We know that most pre-kindergarten programs do a good job of improving ‘ specific skills like phonics and counting, as well as broader social and emotional behaviors, by the time students enter kindergarten. Just this week, a study looking at more than 20,000 students in a state-funded preschool program in Virginia found that kids made large improvements in their alphabet recognition skills.

So the next big question to follow is, of course, Do these benefits last?

New research out of North Carolina says yes, they do. The study found that early childhood programs in that state resulted in higher test scores, a lower chance of being held back in a grade, and a fewer number of children with special education placements. Those gains lasted up through the fifth grade.

The research, published this week in the journal Child Development, studied nearly 1 million North Carolina students who attended state-funded early childhood programs between 1995 and 2010, and followed them through fifth grade.

They concluded that the benefits from these programs grew or held steady over those five years. And when the researchers broke the students down into subgroups by race and income — they found that all of those groups showed gains that held over time.

“Pre-kindergarten and early education programs are incredibly important,” says Kenneth Dodge, the lead author on the study and the director of the Duke Center for Child and Family Policy. “Especially for parents, for business leaders — because of the workforce development aspect — and for policy makers who are spending the money on it.”

This new research confirms what researchers recently found in Tulsa, Okla. – one of the most highly regarded preschool programs in the country. In that study, children who attended Head Start had higher test scores on state math tests up through eighth grade.

Eearlier studies have found the positive effects fade as students move into elementary school — this large study from Vanderbilt is one of them.