How old is Holden's sister Phoebe?

Holden’s sister Phoebe is 10 years old.

Phoebe Caulfield is Holden’s younger sister and the family member he trusts most. Holden describes her as intelligent, lively, affectionate, and unusually perceptive. Although she is still a child, she often understands his emotional problems more clearly than the adults do. When Holden visits her secretly in New York, she quickly realizes that his expulsion from Pencey is part of a larger crisis.

Phoebe also helps Holden articulate his fantasy of being the “catcher in the rye,” protecting children from falling over a cliff. Later, when Holden plans to leave New York, she tries to go with him. Her refusal to abandon him—and their visit to the Central Park carousel—helps him reconsider his escape plan.

Phoebe is six years younger than Holden, who is 16 during the main events. Readers sometimes confuse her age with the ages of Holden’s other siblings, especially Allie, who died before the novel begins.