Girls have been outperforming boys in American schools for decades, from elementary school through college. But the gender gap in education starts even earlier: Boys enter kindergarten less prepared than girls, and this early deficit can compound and help explain some of the recent struggles of boys and young men.

Across measures of kindergarten readiness — including reading, math, motor skills and behaviors like socializing, paying attention and regulating emotions — girls score higher than boys.

These are averages, and researchers emphasize that there are many boys with strong skills and girls with lagging skills. Other factors also contribute — the gaps in kindergarten readiness by family income and by race are larger than they are for gender.

But over the last two decades, as those gaps have narrowed, the gender gaps have become more consequential. Kindergarten has become significantly more academic because of the effects of a national law passed in 2001, with children expected to spend more time sitting still and learning math and reading — and many boys do not enter with the skills to meet those expectations.

Adding to that, childhood has changed in recent years in ways that could have set back boys further. The isolation of the pandemic delayed young children’s development, parents are increasingly stressed, and children are spending more time on screens. These factors affect all children, but they may have been particularly hard on boys, who scientists have shown are more vulnerable to hardship.