One of politicians’ favorite pastimes is telling us how universal preschool is the cure for all our ills, including low student achievement, a sluggish economy see here, here, and here, for example).

A recent report by David Armor for the Cato Institute pulls the evidence together:

Any program that could cost state and federal taxpayers $50 billion per year warrants a closer look at the evidence on its effectiveness. …

The most methodologically rigorous evaluations find that the academic benefits of preschool programs are quite modest, and these gains fade after children enter elementary school. This is the case for Head Start, Early Head Start, and also for the “high-quality” Tennessee preschool program. 

Armor reviews the “evidence” on more recent programs touted by government preschool supporters, and finds suspect and even shoddy research methods to call into question any claims of “effectiveness.”

As the Heartland Institute’s Joy Pullman sums up:

While 15 states this week begged the Obama administration to direct programs for their youngest children, Indiana decided to chart its own course, with Gov. Mike Pence (R) refusing to sign off on an expensive, intrusive federal preschool grant application.  …

The Cato report shows the studies that supposedly find preschool will end all our education and economic woes are misleading and typically based on three boutique programs from 50 years ago that were nothing like current preschool programs or proposals.

At best, government preschool is an early remediation possibility for children in mind-starved home environments, and it may be able to help some of these children avoid jail and graduate from high school. But so far, very enthused teachers and researchers, even with lots of money, have only been able to take tiny steps towards these laudable goals. That’s no reason to push government preschool programs. Far better to take the millions in private dollars currently expended trying to get lawmakers to coerce taxpayers into funding such highly speculative programs and send them to valid, well-planned research groups.