In what way is Peter Pan about growing up?
An ethereal creature, Peter Pan lives in a boyish fantasy world in which life consists of flying around, adventure, fighting pirates, and just having fun. And, as Barries writes, "Children have the strangest adventures without being troubled by them." For, his dangerous encounters with Captain Hook, for example, do not disturb Peter. In Act III of the stage production, for instance, Wendy, who has assumed the role of mother for the Lost Boys, relating fairy tales and such to them, wishes Peter to consider himself her husband. But Peter refuses and is only willing to pretend this role, preferring instead for Wendy to consider him like a son. In Act IV, when he hears Wendy refer to her mother's having left the window open in hopes of her children's return, Peter becomes anxious and refuses to join Wendy in any efforts to return eschewing responsibility.
Peter's fear of growing up is also evinced in his allusions to growing old and eventually dying as opposed to his life in Never Land where he can remain young. Peter's meeting with Mrs. Darling evinces his dislike for grown-ups as when he saw she was a grown-up, "he gnashed the little pearls at her." Finally, in Act V after Wendy and her brothers return home, Peter will not allow himself to be adopted by the Darlings, choosing to agree to the Darlings offer that Wendy can visit Never Land every spring.
Clearly, Peter's refusal to accept responsiblities and to live in a fantasy world convey the theme of Duty and Responsibility, a theme with implications of growing up. The setting of fantasy and the adventures that are like those of an imaginative boy imply Peter's escape from responsibility and duty, those elements of maturation.