Another NBER working paper released this month addresses a different approach to improving life outcomes for kids that’s gaining much more traction among state and federal policymakers: Universal childcare. Its findings actually make a universal basic income seem even more appealing. (Matt Yglesias was the first to point this out on Vox.)

Coauthored by one of the Affordable Care Act’s chief architects, the paper studies the long-term effects of Quebec’s daycare program, “North America’s best-known experiment in universal preschool care and education.” Contrary to what you might expect, it shows that children exposed to the program have suffered significant negative behavioral and emotional effects.

Among eligible young children, the authors found that the Quebec program lead to increases in anxiety and aggression. There was "a significant worsening in self-reported health and in life satisfaction among teens" who’d been exposed for the program. And compared to children in other provinces, the Quebec cohort also showed a "sharp and contemporaneous increase in criminal behavior" as they entered adolescence.

The program, which was introduced in 1997, wasn’t a complete disaster. By providing heavily subsidized slots in nonprofit daycare programs to any working parent in Quebec, it was successful by some measures: Adults’ participation in the labor force, especially among mothers of young kids, increased significantly. And enrollment in the program boomed.

But their kids suffered, winding up worse off than peers who’d never had daycare at all. It seems that the high demand for slots diluted the quality of the children’s care: After highly rated nonprofit programs filled up, the government had to resort more and more to lower-rated private and in-home services.

Quebec’s system is probably distinct from what the U.S. might offer, if universal childcare was adopted here. And the NBER study has yet to be published; among the many variables that intervene in children’s lives between daycare and adolescence, there could certainly something that the researchers missed that affect these results.

Nevertheless, there is an important lesson here: When supply and funding are limited, it’s extremely hard to maintain quality at such a large scale. And if you can’t offer the same care or educational experience to every child—something that’s truly “universal”—you should probably rethink the approach. That’s the basis of most criticism of universal pre-K and childcare here in the U.S., where paltry state and federal funds have already helped created a crisis in K-12 education.

"You have to look at the trade-off," Darleen Opfer, education director at the RAND Corporation, told The Atlantic in 2014. "If you have a state that can’t afford high-quality preschool for everyone, where does the investment really make sense? To me it’s not an issue of whether or not [pre-K is] a good thing… The clashes come over how to do it."