Pennsylvania parents can expect to shell out $10,500 per year on private-sector preschool. In Philadelphia, the price can range from the $4,500 per year for full-day preschool at St. Francis Xavier School to more than $12,000 at the elite Gladwyne Montessori School.

Head Start, the government-run preschool program, costs federal taxpayers $8,000 per child annually. Though not the cheapest program available, it beats the average private-sector cost by a significant margin. So it must be a good deal, right?

Not so fast. Head Start seems to have a lot going for it. Children enrolled in the program must attend preschool in Head Start centers, run by Head Start teachers, "accountable" to the federal Department of Health and Human Services. Except there's actually no accountability.

Indeed, time after time, the Great Society program has proved ineffective in preparing children for academic success. After 48 years and $180 billion in taxpayer money, the program has yet to demonstrate any lasting improvement in educational or social outcomes.

The promise of Head Start is a deception propagated on America's low-income families. For nearly a half-century, poor parents have enrolled their children in what they believed was an "educational" program.

But a recently released evaluation of Head Start, mandated by Congress, reveals the hollowness of that promise. Published by the U.S. Department of Health and Human Services (HSS), the report reveals that Head Start failed to improve the cognitive abilities of children, their access to health care, and the parenting practices of participants.

What's particularly alarming is that access to Head Start actually has some negative impacts on enrolled children. In addition to having little to no impact on the cognitive, social-emotional, health, or parenting practices of its participants, federal researchers reported worse peer relations and lower teacher-assessed math ability for Head Start children.

This latest evaluation is important because of its design. The study tracked 5,000 children who were randomly assigned to either a group receiving Head Start services or a group that did not participate in Head Start. It followed their progression from ages 3 or 4 through the end of third grade, and was a continuation of HHS's Head Start Impact Study, which followed children through the end of first grade.

This design is scientifically rigorous. It allows us to say, without a shadow of a doubt, that exposure to Head Start itself results in poorer outcomes for poor children.

Parents and taxpayers deserve to be informed of what HHS found: Access to Head Start had no statistically measurable effects on cognitive ability, including numerous measures of reading, language, and math ability. They also deserve to know why it took HHS so long to make this information available.

The sad fact is, HHS withheld their findings for four years. Data collection for the evaluation was completely finished in 2008, but the report was only just released. Even once it was printed - the publication date on the cover is October 2012 - the agency allowed it to sit, unread and collecting dust, for two months more. HHS finally released it on the Friday before Christmas - a date that promised the greatest likelihood of it going unnoticed. Clearly the department was not enthusiastic about releasing such definitive evidence that Head Start fails children.

Taxpayers should also know that Head Start is just one of 69 federal preschool programs - scattered among 10 federal agencies - that cost $25 billion annually. Federal child-care and preschool programs are housed in the Department of Education and Department of Health and Human Services, but also in the Departments of Agriculture, Labor, Housing and Urban Development, and even the General Services Administration, among others.

The latest evaluation of Head Start by HHS shows once again that this relic of the Johnson administration needs to be placed on the chopping block. If, however, the federal government continues to fund child care, states should at a minimum be allowed to make their Head Start dollars portable, following children to any preschool provider of choice.

That might not pay for enrollment at the poshest pre-K provider in Gladwyne, but it would certainly cover the cost of many quality preschool options in Philadelphia. So instead of relegating poor children to underperforming Head Start centers, if the federal government continues to fund child care, providing states with more flexibility over how they use Head Start funds has far greater potential to better serve families.

-Lindsey M. Burke is the Will Skillman Fellow in Education Policy at the Heritage Foundation