In and , Mark Twain introduced two of the most iconic boys in American literature. Tom and Huck become heroic figures, despite their penchant for bad behaviour. Indeed, it is their propensity to be impulsive, break rules and defy authority that win them the day. Today, however, Tom Sawyer and Huck Finn have become the posterboys for a psychiatric disorder, Attention Deficit Hyperactivity Disorder, or ADHD. I trace how and why attitudes about pathological boys' behaviour reversed during the twentieth century, from a focus on shy, introverted, and physically passive boys to the very opposite - boys like Tom and Huck. I argue that, rather than imposing limits on childhood behaviour, we should be more accepting and encouraging of all types of children.