What is the significance of Junior’s two names, Junior and Arnold, in The Absolutely True Diary of a Part-Time Indian?

The two names represent the two selves Junior struggles with as he attends Reardan. Arnold Spirit Jr. is his given name, the name he uses at Reardan, his white name, and the one accepted by authorities. Junior, a common Native American nickname, is the name every other person on the reservation calls him. Junior’s confusion over which name to use at school exemplifies his confusion over who he is and who he can choose to be. Going by Arnold shows he’s trying on a new identity. Names are a key aspect of selfhood, and Junior decides to change the name he goes by since he also wants to change his life. When the Native American audience chants his Reardan name, Arnold, in the basketball game, he knows they’re mocking his school identity, his “white” self.