Wonder is a work of fiction. However, author R. J. Palacio says that the story was inspired by a real-life encounter she had when she was out with her own son, who was then a small child in a stroller. Her son saw another child who had a facial disorder like that of Auggie Pullman, the protagonist of Wonder. The author relates that her son was so upset by seeing the other child that he began to cry and that she recognized that the other child, the inspiration for Auggie, probably faced episodes like that almost every day of her life.

Palacio has also said in interviews that her impulse was to shield the other child from her son's reaction and from his tears. The message in the book is to move past this sort of initial reaction to physical appearance and get to know the other person. Auggie is a special boy, not because of his facial disorder, but because he is kind, sympathetic, bright, engaging, and compassionate.

Wonder is a fictionalized account of what it must be like for a child with a craniofacial disorder and the child's family to navigate life. It is not surprising that families who have lived with similar situations have connected with Wonder. As a result, there are families who feel that Auggie and the Pullmans represent their own true stories. Many have reached out to Palacio to thank her for bringing their stories to light.