Female classmates boost mental health

Using Add Health data and within‑school cohort variation, researchers find that a higher proportion of female peers improves mental health for both boys and girls, with the largest gains for low‑income boys. Boys report greater school satisfaction; mechanisms include stronger friendships for boys and better self‑image and grades for girls. — This points to class composition as a policy lever for student well‑being and discipline, informing co‑ed vs single‑sex debates and school design beyond curriculum fixes.