From Peter Gray's blog, here are the official diagnostic criteria for ADHD:
Inattention
1. Often does not give close attention to details or makes careless mistakes in schoolwork, work, or other activities.
2. Often has trouble keeping attention on tasks or play activities.
3. Often does not seem to listen when spoken to directly.
4. Often does not follow instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behavior or failure to understand instructions).
5. Often has trouble organizing activities.
6. Often avoids, dislikes, or doesn't want to do things that take a lot of mental effort for a long period of time (such as schoolwork or homework).
7. Often loses things needed for tasks and activities (e.g. toys, school assignments, pencils, books, or tools).
8. Is often easily distracted.
9. Is often forgetful in daily activities.
Hyperactivity & Impulsivity
1. Often fidgets with hands or feet or squirms in seat.
2. Often gets up from seat when remaining in seat is expected.
3. Often runs about or climbs when and where it is not appropriate (adolescents or adults may feel very restless).
4. Often has trouble playing or enjoying leisure activities quietly.
5. Is often "on the go" or often reacts as if "driven by a motor".
6. Often talks excessively.
7. Often blurts out answers before questions have been finished.
8. Often has trouble waiting one's turn.
9. Often interrupts or intrudes on others (e.g., butts into conversations or games).
Peter Gray asks "who is surprised that so many boys have been diagnosed as having ADHD?"
I don't really know about boys, but I can see that each of my daughters fits these criteria perfectly. My older daughter is a textbook case of "Inattention", and my younger daughter is a textbook case of "Hyperactivity & Impulsivity". Actually, I'm amazed that, at least so far, nobody's tried to label either of my kids "ADHD". Perhaps school personnel can predict my likely response?
And here's the Onion's take on it: More US Children Being Diagnosed with Youthful Tendency Disorder.