Boy, Snow, Bird is a commentary on race in America filtered through the familiar story of Snow White. Boy, despite being a sympathetic narrator, fills the evil stepmother role. She becomes enchanted by Snow's beauty. Then, when she feels threatened by Snow's ability to pass herself off as a white woman, Boy sends her stepdaughter away.

Appearances are very important in Boy, Snow, Bird, and—just like in Snow White's story—mirrors serve as a motif. There may be no Magic Mirror, but mirrors in Oyeyemi's novel are just as otherworldly. They are a means for characters to wrestle not just with their outward appearance, but also with their identities. Bird is fascinated by reflection and perception and claims that sometimes she has no reflection at all. She spots a girl in the forest, and it is never clear if she is seeing another person or just a reflection of herself.

In Boy, Snow, Bird, one's sense of self and the way one is perceived by others are inextricable from each other. There is no "true" identity; everything is subjective—especially when it comes to race. The characters in Boy, Snow, Bird—particularly Snow, with her ability to pass—illustrate how one's identity is prescribed to them externally according to their race. Once it is discovered that she is African American, Snow's entire life changes in an instant, largely due to Boy's resentment of Snow's perceived whiteness. The book makes the claim that it is what others see in our appearance and actions that count and not who we are fundamentally or even genetically. Race in America is a matter of perception.