The Heritage Foundation talks about three recent studies on government-run pre-K programs.

The Head Start Impact Study. In late 2012, the Department of Health and Human Services released the Head Start Impact Study, a scientifically rigorous evaluation that tracked 5,000 three-year-old and four-year-old children through the end of third grade. The study found little to no impact on the parenting practices or the cognitive, social-emotional, and health outcomes of participants. Notably, on a few measures, access to Head Start had harmful effects on participating children.[7] For both the three-year-old and four-year-old cohorts, access to Head Start had no statistically measurable effects on any measure of cognitive ability, including reading, language, and math.[8] In other words, by the time they finished third grade, there was no difference between those children who attended Head Start and the control group of their peers who did not.

Vanderbilt Tennessee Voluntary Pre-K Study. In 2015, a team of researchers from Vanderbilt University released an evaluation of Tennessee’s Voluntary Pre-K (VPK) Program, a state-subsidized preschool program open to low-income children in the state. Some 18,000 children participate in the program, which was introduced in 1996. Proponents have long claimed Tennessee’s VPK program is a model state-based preschool program, with standards aligned to the Obama Administration’s Preschool for All initiative.[9] Teachers must be licensed, the child-adult ratio is limited to 10:1, and a structured “age-appropriate” curriculum must be used in classrooms. The program is available first to children from low-income Tennessee families, and then, space permitting, to children with special needs and children with limited English proficiency, among other children deemed “at-risk.” An earlier evaluation found that gains made by participating four-year-olds had faded by kindergarten. In a follow-up evaluation released in September 2015, Mark Lipsey, Dale Farrar, and Kerry Hofer reported that there were no sustained benefits for the same children through the end of third grade.[10]

[…]The authors analyzed the VPK program’s impact on children’s math skills, emergent literacy, and language skills, as well as the program’s impact on non-cognitive measures, such as behavior. “By the end of kindergarten, the control children had caught up to the TN-VPK children and there were no longer significant differences between them on any achievement measures. The same result was obtained at the end of first grade using both composite achievement measures.” And notably, by second grade, “the groups began to diverge with the TN-VPK children scoring lower than the control children on most of the measures. The differences were significant on both achievement composite measures and on the math subtests.” “Pre-K was generally thought to be better than Head Start, but that doesn’t seem to be the case in Tennessee,” stated University of California, Berkeley professor David L. Kirp in The New York Times.[11]

The findings of the TN-VPK program were not limited to academic outcomes. As Lipsey et al. explain:

In terms of behavioral effects, in the spring the first grade teachers reversed the fall kindergarten teacher ratings. First grade teachers rated the TN-VPK children as less well prepared for school, having poorer work skills in the classrooms, and feeling more negative about school. It is notable that these ratings preceded the downward achievement trend we found for VPK children in second and third grades.[12]

Quebec’s Negative Non-cognitive Results. The province of Quebec introduced universal low-cost day care for children through age four beginning in 1997. The program has had a large impact: privately funded child care arrangements have almost disappeared, and Quebec has the highest rate of subsidized child care in Canada, at 58 percent in 2011.[13] The program caused a 14.5 percent increase in the share of mothers of young children working outside the home.[14] The Quebec experience offers more guidance for the potential introduction of universal child care than small, targeted programs, because it implicitly includes indirect effects on non-participants and any general equilibrium effects due to the drastic shift in the way child care was funded and conducted.

Regrettably, new research has found that children who became eligible for the program in Quebec were more anxious as children and have committed more crimes as teenagers. The availability of day care clearly worsened children’s non-cognitive “soft” skills.

Michael Baker, Jonathan Gruber, and Kevin Milligan found that children exposed to the program were 4.6 percent more likely to be convicted of a crime and 17 percent more likely to commit a drug crime. Their health and life satisfaction were worse.

The programs are sold as a way of improving children’s abilities, but the studies show that it doesn’t work that way. So why do we have these programs?

Democrats like these programs because they transfer wealth from taxpayers to government, hire more government workers, and get children away from the “harmful” influence of their parents. It allows the government workers to push the agenda of the wealthy donors who back the Democrat politicians, e.g. – the abortion providers, the gay rights activists, the terrorism apologists, the global warming alarmists, the radical feminists, the socialist wealth redistributors, etc.