Though it is ultimately a children's adventure story, The Adventures of Tom Sawyer's main message regards coming of age. Tom is a young boy bordering on adolescence, and his adventures push him further into the adult world. As a result, he becomes a more involved member of his community, even putting his life on the line for its sake.

Tom's adventures make him more responsible and selfless. For example, he takes a whipping for Becky when he accepts the blame for the schoolbook she damaged. Most significantly, he risks his own safety in testifying against Injun Joe, because he knows more lives will be at stake if he does not. Injun Joe is a social outsider who, unlike the outsider Huck Finn, represents a threat to the community: he has committed murder and robbery, has desecrated a grave, and plans on attacking the Widow Douglas. Tom, representing the values of community and civilization, opposes Joe and ultimately helps bring him to justice.

Though Tom is imaginative and rambunctious, he becomes a more moral and responsible child by the end of the book. Therefore, while the book celebrates the many unique qualities of childhood, it does also celebrate the greater maturity that comes with growing up and becoming a part of the adult community.