The Absolutely True Diary of a Part-Time Indian is semi-autobiographical. The novel started as a section of Sherman Alexie's family memoir, but after the persistence of a young adult editor, he decided to use it as a basis for his first young adult novel. Sherman Alexie commented, "If I were to guess at the percentage, it would be about seventy-eight percent true."  Like Arnold, Sherman Alexie grew up on the Spokane Reservation in Wellpinit with an alcoholic father. He was also born with hydrocephalus, but Alexie did not have any speech impediments. Alexie was also teased for his government-issued, horn-rimmed glasses and nicknamed "The Globe" by fellow students because of his giant head. Another similarity between Alexie and his character Arnold is that Alexie also left the reservation to attend high school at Reardan High, but Alexie chose to go to Reardan to achieve the required credits he needed to go to college. Alexie became the star player of Reardan's basketball team, and was the only Indian on the team besides the school's team mascot. The scene where Arnold finds that he is using the same textbook his mother did thirty years before him is drawn from Alexie's own experiences. The only difference from Alexie's life and the novel is that Alexie threw the book against the wall out of anger, and did not hit anyone like Junior did.
In his own writing, Alexie unapologetically describes himself as "kind of mixed up, kind of odd, not traditional. I'm a rez kid who's gone urban, and that's what I write about. I have never pretended to be otherwise." "A smart Indian is a dangerous person," Alexie states in a personal essay, "[a smart Indian is] widely feared and ridiculed by Indians and non-Indians alike."  Junior encapsulates this type of experience when he receives strong censure both from his tribal community and from his peers and teachers at his new school, Reardan. In the personal story, Alexie's continued explanation of his own experience is reflected in Junior's. Alexie recalls, "I fought with my classmates on a daily basis. They wanted me to stay quiet when the non-Indian teacher asked for answers….[W]e were Indian children who were expected to be stupid. …[W]e were expected to fail in the non-Indian world."  Through Junior's success at Reardan and his realizations about life on the reservation, Alexie represents a possibility for the success of Native American children—by defeating the expectation that he is doomed to fail, Junior crosses social boundaries and defeats unfavorable odds. Alexie's reflections again demonstrate that Junior's experiences are semi-autobiographical.