On Oct. 17, families at Harvard-Westlake School in Los Angeles received news they must have been dreading for more than a year.

A ninth grader had died at home that morning. “It is important for us to share with you” that the student took his own life, the school said.

The death of a 15-year-old, whom a classmate later described as someone who “defined the meaning of greatest friend,” would have been tragic at any school. But at Harvard-Westlake, popular among the Hollywood elite, it was the fourth student to die this way since March 2023. Other community members had recently ended their lives too.

Young people are taking their own lives at higher rates than before, and at Harvard-Westlake, the rate appears to be even higher. Sheila Siegel, a former Harvard-Westlake parent and longtime psychologist at the school, recalls experiencing just one student suicide in her more than two decades there,...