With his letter, Dr. Aderhold inserted West Windsor-Plainsboro Regional School District into a national discussion about the intense focus on achievement at elite schools, and whether it has gone too far.

Image A button produced in support of the "Take Back Childhood" movement started by Ms. Foley, a local parent who has come to see the district’s high-pressure atmosphere as antithetical to learning. Credit... Mark Makela for The New York Times

At follow-up meetings, he urged parents to join him in advocating a holistic, “whole child” approach to schooling that respects “social-emotional development” and “deep and meaningful learning” over academics alone. The alternative, he suggested, was to face the prospect of becoming another Palo Alto, Calif., where outsize stress on teenage students is believed to have contributed to two clusters of suicides in the last six years.

But instead of bringing families together, Dr. Aderhold’s letter revealed a fissure in the district, which has 9,700 students, and one that broke down roughly along racial lines. On one side are white parents like Catherine Foley, a former president of the Parent Teacher Student Association at her daughter’s middle school, who has come to see the district’s increasingly pressured atmosphere as antithetical to learning.

“My son was in fourth grade and told me, ‘I’m not going to amount to anything because I have nothing to put on my résumé,’ ” Ms. Foley said.

On the other side are parents like Mike Jia, one of the thousands of Asian-American professionals who have moved to the district in the past decade, who said Dr. Aderhold’s reforms would amount to a “dumbing down” of his children’s education.