Lauren,
The developmental behavioral pediatrician did base the diagnosis largely on parent and teacher questionnaires. They were very extensive questionnaires, and you do rate many behaviors on a severity scale. Once we begin medication, we continue to do the questionnaires on a regular basis to measure changes in behavior.

There are criteria that must be met to make a diagnosis. For example, the symptoms have to exist in multiple settings, must be present for an extended period and present before a certain age, and the behaviors/inattention must affect the child in some functional and/or educational way. In addition, they do tests to rule out other possible causes, like oppositional defiance, anxiety, schizophrenia, and other psychological and/or physical conditions. I like the idea of seeing the developmental ped b/c she checks for developmental, neurological, and learning disabilities as well. In fact, there's one thing she tested for, can't remember what it's called, where she asked ds to perform some tasks that required him to move one side of his body. She looked to see if he moved other parts of his body as well. She found with my ds that when asked to touch his left shoulder with his right hand, for example, he also moved his left hand and his tongue. He's notorious for moving his tongue when performing other physical tasks like playing basketball or writing. She said this is very typical with children with ADHD, so it just provided more corroborating evidence for the diagnosis. I feel much better going this route. I don't think I would have trusted any school to diagnose ADHD. How old is your son?