RALEIGH – Upon the release of the latest findings from a long-running National Institute of Child Health and Human Development study of child care in the United States, most reporters and policymakers immediately zeroed in on perhaps the most controversial discovery: that quite apart from its quality, day care appears to correlate with behavior problems well into the late elementary-school grades.

Time to wage another round of the Mommy Wars, some thought. Time for the day-care industry to spend a lot more time and money defending its services.

For me, though, this finding was not the right subject for the headline. If you look at the underlying data from the NICHD Study of Early Child Care and Youth Development, the day-care effect on child behavior may have been statistically significant, but in practical terms it was modest. It would be wrongheaded to cite the study as “proof” that today’s chaotic public-school classrooms or overcrowded juvenile-justice system are the inevitable result of mothers choosing to work outside the home. The day-care factor couldn’t possibly account for most of these (distressing) social indicators and conditions.

No, to my mind the policymaking implications of the new study, published in the March-April edition of the journal child Development, were to be found elsewhere.

Beginning in the early 1990s with Gov. Jim Hunt’s Smart Start initiative, North Carolina has been a prominent national exemplar of the notion that “investing” in early-childhood programs could pay substantial returns in student achievement and other improvements later on. Smart Start quickly secured an annual budget in the hundreds of millions. Gov. Mike Easley’s contribution to rhyme-time politics, More at Four, advanced the idea that while preschool in general might be a legitimate and productive use for state taxpayer funds, targeting money to at-risk four-year-olds would offer the best opportunity to make a meaningful difference (an idea I have always agreed with, by the way).

The problem is that, contrary to the claims of both gubernatorial administrations, there was little empirical or theoretical justification for believing that these programs would, in fact, produce anything like the promised results. Yes, there were a couple of laboratory experiments that had yielded promising results for desperately poor children placed in expensive, carefully controlled day-care environments. But the sample sizes were relatively small. And it was never reasonable to believe that such laboratory results could be replicated in large-scale, statewide programs funded and run by government agencies.

Indeed, early evidence from Smart Start and More at Four has suggested that whatever gains participating students exhibited compared with otherwise-similar non-participants, they were so small that, as in previous experience with Head Start, the gains were unlikely to persist past the second or third grade. This widely known phenomenon is called the fade-out effect.

For the most part, the new NICHD study results confirm this unfortunate prediction. What researchers termed “high-quality day care” – care by an engaged, responsive adult in a rich, nurturing setting – did not lead to any lasting gains for fifth-graders in reading or mathematics. Participants had exhibited slight gains in each subject when they were younger, but the effects had faded out by fifth grade. On the other hand, the study did confirm the persistence of gains in vocabulary among fifth-graders who had gone through high-quality day care. But, as with the negative behavioral effects, the impact was modest.

Far too many policymakers in North Carolina and elsewhere have seen early-childhood intervention as a way for the government to inoculate disadvantaged students against the adverse effects of poverty, bad parenting, and shoddy schooling. It won’t work. Parenting is by far the largest factor affecting student success – and is largely outside of the control of government, at least in a free society. The other large factor is the quality of schooling, which policymakers can and should address.

In other words, the problem is not – as the education establishment prefers to frame it – that children don’t spend enough years in government programs. The problem is that the years our children do spend in government schools are not being used productively. There are alternative education policies the offer a realistic prospect of much-larger gains than preschool intervention. Let’s get cracking.

Hood is president of the John Locke Foundation.