For much of Bud, Not Buddy, Bud is instinctively distrustful of the adults around him. As a child who has been mistreated by so many of them, Bud’s hesitance is framed in the narrative as self-defense rather than prejudice. Indeed, his first notable interaction with new adults—the Amos family—ends in his being blamed for a fight and locked in a dark backyard shed, where he is attacked by wasps.

In the absence of an overarching authority in his life, Bud becomes self-reliant and constructs a belief system of his own: “Bud Caldwell's Rules and Things to Have a Funner Life and Make a Better Liar of Yourself.” These rules are, for the most part, about how to negotiate his safety among adults. For example, in one rule he recommends misdirecting adults toward something trivial that they can take away from him to maintain their power. This, he explains, keeps them from taking away what he truly does value.

These guidelines give him a touchstone as he contemplates his own maturity and sense of awareness, which he does often. Through his deliberate opposition to the adults around him, Bud is constantly defining and evaluating his own identity as separate from them. "Most folks think you start to be a real adult when you're fifteen or sixteen years old," he muses in chapter 1, "but that's not true, it really starts when you're around six."

As his journey continues and he meets adults who treat him better—Lefty Lewis and his family, Miss Thomas and the other members of the band—he begins to relax and to trust adults more. As he makes room for that trust within himself, he matures enough to see the members of the band as not just adults but also friends. The novel ultimately suggests that even the most independent individuals can, in the right conditions, find a sense of belonging and community.