Black Boy is Richard Wright's story of his own past, so it is, ostensibly, a memoir. But its narrative style is more complex than most memoirs, and in fact is more akin to a novel.
Wright uses directly quoted dialogue and stylized descriptions that read more as contrived fiction than true memoir. In a more contemporary term the book might be called "autofiction": a work presented as a fictional novel but also explicitly based on the true events of an author's life. In this way the book can also be called a bildungsroman, a coming-of-age story, but it is unusual in that it is written by the protagonist of the tale. To reiterate, the text is often not presented as a memoir: the focus is on a narrative progression of events with intentional pacing and fully-fledged characters, making the text read like a novel, but have the content of a memoir.
Wright is also part of a movement of African American writers of the South in the early 20th century that aimed to, for the first time, depict Black life in literature. In this genre Wright is joined by Zora Neale Hurston, author of Their Eyes Were Watching God and regular literary opponent of Wright's, as well as James Baldwin, author of dozens of novels and books of criticism and a notable criticism of Wright's novel Native Son. The authors in this genre often clashed over style and perspective. Wright, in Black Boy especially, attempted to depict Black life as it truly was, with a great deal of suffering, in energetic, journalistic prose that aimed for accuracy over beauty. Hurston, on the other hand, used the medium of the novel as an opportunity to depict joy and suffering for Black people among themselves, without the involvement of quite so much overt White racism. Black Boy is an important work in this tradition as well, as Wright aims to dramatize his own life with the narrative accuracy of his magnum opus, the novel Native Son. Black Boy is a continuation of the growth of this genre of African American literature in the United States in the decades after the Harlem Renaissance.