The largest study of school cell phone bans to date offers a mixed report card: locking up students’ phones cuts in-school use markedly, but the policy does not quickly raise test scores, improve attendance or reduce bullying, according to a working paper circulated Monday by the National Bureau of Economic Research. The analysis, led by Stanford economist Thomas Dee and colleagues at Duke, the University of Michigan and the University of Pennsylvania, draws on data from approximately 4,600 U.S. schools that adopted lockable pouches made by the California startup Yondr — the first nationally representative look at enforced bans rather than honor-system “no‑show” policies.
The phone-use effects were immediate and substantial. Teacher surveys showed the share of students who said they used phones in class for personal reasons tumbled from 61% to 13% in schools with all-day bans. GPS data from devices on campuses with Yondr pouches showed a “large and persistent decline” in total pings during school hours, dropping about 30% by the third year. The researchers caution that the ping data include adult devices and that a phone can ping while not in active use, but they say the figures represent a “conservative lower bound” on the change in student phone use.
On discipline, the study found that in-school and out-of-school suspension rates climbed roughly 16% in the first year a ban was in effect. The uptick likely reflected schools taking enforcement seriously, as well as students turning to other disruptive behaviors when phones were taken away, Dee said. By the third year, however, suspension rates had fallen back to their pre‑ban levels.
Students’ self‑reported well‑being also declined in the first year, then recovered. “Within three years, students’ well‑being is actually above what it was at baseline,” Dee said.
On standardized tests, average effects were “consistently close to zero” across the first three years after adoption, with similar results in reading and math. Dee called the findings “sobering” and “somewhat disappointing.” But he noted that the newest cohort of schools, which adopted bans in 2024, actually recorded test‑score gains in a short time. He speculated that the social context around phone bans may be shifting: “I think people are much more likely to see phone bans in a beneficent light now, as something that’s meant to help us rather than constrain us, even relative to several years ago.”
The study found effects on attendance were “close to zero,” and there were no measurable improvements in perceived online bullying or self‑reported classroom attention.
Dee emphasized that reducing phone use is a necessary first step. “I firmly believe that getting student phone use down, recapturing their attention in classrooms within schools, is a critical antecedent to realizing their academic potential,” he said, urging schools to persist. “We need to not succumb to the usual faddishness that permeates education reform and persist with a robust learning agenda that will allow us to figure out how to manage digital devices and support child development.”
The study lands as at least 37 states and the District of Columbia have mandated districts to restrict phone use, and public support has risen — 74% of U.S. adults now back banning phones during class for middle and high school students, according to Pew Research Center surveys. The psychologist Jonathan Haidt has been a leading advocate for bans, linking smartphones to a surge in teen mental illness. The new findings, however, suggest that while bans succeed in reducing phone use, the academic and social dividends many supporters expect may take years to materialize, and that schools will need to pair the bans with other strategies.